Beepedia

Beepedia A Brief Compendium of Bee Curiosities

Laurence Packer

Illustrations by Ann Sanderson

PRINCETON UNIVERSITY PRESS

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Introduction

What can be more lovely than a bee? After all, they make honey and wax (perhaps not so important since the widespread use of electric light bulbs, but candles are still romantic) as well as pollinating agricultural crops and wild plants. Their behavior is complex but seemingly extremely well organized and efficient. They are also beautiful to look at. Bees are indeed lovely, but most of them aren’t the sweet, productive, socially respectable organisms we normally think them to be. Most are complete loners, a few species feed on carrion, some others on tears, some have workers that gang up on the queen and kill her and eject younger relatives from the colony, sentencing them to an early demise—which may call to mind struggles among family members in (mostly) ancient dynasties. Many species, even as newly hatched “babies,” dismember other individuals, slicing them up in the brood cell using sickle-shaped mandibles. Bees, as a whole, are perhaps not quite so sweet—but certainly far more interesting.

The number of bee species melittologists have described is still increasing, over 270 years after the first one was named. The number as of June 2024 is approximately 20,950 and with so many species it is not surprising that many of them do not fit the standard view of being “lovely” or “busy.” With so many species, there is much yet to discover about them. Some of the more surprising facts about bees—such as tear-drinking or many bees getting more nutrition from the microbes living in their provisions than from pollen—are very recent findings and doubtless many more fascinating discoveries will be made in the future.

Agapostemon

These are among the most obviously beautiful bees in the world; they are also common in Central America, the Caribbean, and parts of South America—and especially in North America. Most species are brilliant, metallic green. The entire body of a female is usually this color but in males the metasoma is most often patterned with transverse yellow and black bands. At least one species has a genetic polymorphism for color in which metallic colors are entirely absent in some individuals: homozygotes—those carrying two copies of the same allele—are either bright metallic or black. Heterozygotes—individuals carrying one copy of the typical color allele and one of the alternative non-metallic one—are dull, dark, metallic blue. As there are no heterozygotes in the haploid males, they are either bright metallic or black and never dull, dark blue.

Several Agapostemon species have females that are brilliant green on the head and mesosoma, but the metasoma is black with white hair bands. One of these—Agapostemon virescens—is abundant in much of North America. It is a communal species, meaning that females share a nest entrance but otherwise do all their own work. The advantage to this is that there is more activity at the nest entrance and this helps keep invading natural enemies at bay. As a result, these bees are happy to let unknown members of their own species into their nest to increase the traffic flow: safety in numbers. Such a welcoming approach to immigrants, as well as its aesthetic beauty, have resulted in this species becoming the Canadian city of Toronto’s official bee species.

See also Body Plan; Communal; Halictidae; Haplodiploidy; Integumental Coloration.

Aggregation

Bees that nest in the ground sometimes do so at great densities, with groups of burrows being called aggregations, which may attain densities of two thousand per square meter and extend over enormous areas. Aggregations provide an abundance of food for natural enemies, so how and why do ground-nesting bees sometimes nest so densely? Small aggregations can start with a single female whose daughters nest close to where they were produced. If bees overwinter beneath their natal nest, digging up to the surface the following year and using that burrow to initiate their own nest will result in a small aggregation. Some bees fly away from their natal nest area to overwinter elsewhere but return the following year, finding their original nesting area with remarkable precision. Single bees may be attracted to an aggregation through sense of smell.

One possible advantage to aggregating nests can be explained in terms of William Hamilton’s (1936–2000) “geometry for the selfish herd” where individuals that are densely surrounded by others are less at risk from natural enemies, which will mostly attack around the periphery. Thus, one might expect bee nests near the center of an aggregation to be less impacted by the numerous enemies that seek to attack them, their brood, or their food. Populations of such enemies are known to build up over time and may cause a population crash of their hosts. This can only happen if the aggregation is at the same site year after year. At least some individuals fly away from their natal aggregation and initiate a new one elsewhere the following year, perhaps as a way of eluding their enemies.

See also Beetles as Natural Enemies of Bees; Flies as Natural Enemies of Bees; Nesting Sites.

Agriculture

Bees are responsible for a great deal of our agricultural productivity. Three-quarters of our food crops require a pollinator. It is not only fruit and vegetables that bees bring us: some meat and dairy production relies on bees. That is because alfalfa is one of the winter fodder crops for cattle and without bees to pollinate it (and alfalfa is a crop for which honey bees are inefficient pollinators), meat and dairy lovers would have to pay more for their cheeseburger. A 2024 study found that wild insects were responsible for approximately one half of all crop flower visits and managed bees, primarily Apis, were responsible for the rest.

Wind pollinated crops such as wheat, corn, rice, oats, and grapes do not need bees, but most of the more nutritious and tasty dietary items do need a pollinator. As many plants have some level of self-pollination, there will often be some yield even in the absence of pollinators, but this yield will be substantially reduced and the resulting product more expensive and often less appealing in appearance.

Examples of crops for which pollination is essential for any yield whatsoever include some squashes, blueberries, avocado, and macadamia nuts. For the first two, honey bees do an acceptable job, but on a per-floral-visit basis, wild bees are far better. For squashes, the logically named squash bees are excellent pollinators.

The number of pollen grains required to produce a good fruit varies, but for watermelon, at least 1,600 pollen grains must be deposited on the female flower’s stigma to prevent a small or misshapen fruit from forming.

See also Alkali Bee; Apis; Pollination; Squash Bees.

Alkali Bee

In parts of Utah and Idaho there are roadside signs that read “DRIVE SLOWLY: ALKALI BEE AREA.” It is not often that speed limits are imposed to help an insect. The alkali bee, Nomia melanderi, is a species of Nomiinae (Halictidae) that is particularly effective at pollinating alfalfa flowers. These flowers need to be “tripped” through specific pollinator actions upon alighting on the flower. Honey bees are poor alfalfa flower trippers, but alkali bees (as well as alfalfa leafcutting bees) are excellent at the job. Nonetheless, honey bees are often used in alfalfa fields because tens of thousands of inefficient workers can do a reasonable job en masse. The alkali bee is the only ground-nesting bee species that has been successfully managed for pollination—indeed, it has even been introduced from its native North America to New Zealand for this purpose. They are likely easier to manage than other bees that nest in the ground because of their unusual, preferred nest sites: alkali salt pans that are common in parts of the western United States, and which give them their common name. Large, naturally occurring aggregations of these bees have been used to “seed” pollinator populations at additional alfalfa growing sites. A block of soil containing overwintering fully grown larvae is simply translocated to the new site and the farmer awaits the emergence of the adults the following summer.

A common name for the alkali bee and some of its relatives is “pearly-banded bees” because of the beautiful, somewhat opalescent transverse bands on their metasomal terga.

See also Agriculture; Body Plan; Pollination.

Andrenidae

The Andrenidae is one of the seven families of bees and with over three thousand species, it is the third largest. Indeed, one of its genera—Andrena—has over 1,600 species and is the second largest bee genus in the world. Andrenidae are found on all continents except Antarctica and Australia. All make their nests in the ground, none of them are cuckoo bees, they are all either solitary or communal, and none are known to have a reproductive division of labor.

There are three subfamilies: the Andreninae, Oxaeinae and Panurginae. The Andreninae consists of relatively few genera and, except for Andrena, each has few species. Most species are found in the northern hemisphere with relatively few in Africa, South America, and tropical Asia. Oxaeinae is made up entirely of a small number of genera each with rather few species. They are restricted to the western hemisphere from the southern United States to Argentina and are rather large, fast, flying bees. The Panurginae is the most taxonomically diverse subfamily of andrenid even though it has fewer species than just the one genus Andrena. Taxonomists (scientists that describe and categorize organisms) have split this group into no fewer than seven tribes and an ever-changing number of genera. These are mostly small bees, including Perdita minima, which, at less than 2 millimeters in length, is the smallest bee on the planet. Most are oligolectic, using pollen from a single flower species or a few closely related ones.

See also Biogeography; Classification; Oligolectic.

Antennae

The basic structure of a bee antenna is to have one relatively large segment, called the scape, followed by a relatively small, round one, called the pedicel, and then a third segment that is subdivided into additional sections. This last piece is called the flagellum and it is divided into flagellomeres though they are often imprecisely referred to as segments. Bee antennae are useful for us as they help to tell males apart from females: males have eleven flagellomeres, females ten. As always, there are exceptions in which the males also have ten. But there are some extreme examples, the best known being the “spiral-horned bees” in which some males can have as few as eight flagellomeres and the last two are tiny.

Antennae are useful to bees because they aid in sensing their environment, both chemically and physically. Unlike moths and some other insects, bee antennae are not elaborated into fans or feather-like structures. They generally do not have flagellomeres that are branched—though there are a couple of exceptions. One is the males of a rather uncommon Australian colletid bee Cladocerapis bipectinatus, which have flagellomeres that are extremely complicated in structure, each one looking like part of a Christmas tree with baubles attached. As with other insects, the bee antenna is the major organ of smell—for males, it is mostly the female pheromones that are of interest. For females, identification of their nest site (or for cuckoo bees, finding the host nest) and location of preferred floral resources are important functions of the sense of smell.

Antennae also have tactile functions, with some males having serrated antennae, and some even seem to be involved in visual communication with the last flagellomere forming a large, flat disk attached to the end of a narrow thread perhaps acting as a semaphore signaling device.

See also Sexual Dimorphism.

Apidae

This is one of two families of long-tongued bees and can be differentiated from the other long-tongued bee family—the Megachilidae—by the labrum (like an upper lip, between the base of the mandibles) narrowing at the base and scopa (if present) on the hind leg rather than on the metasoma. It contains the largest number of species of any bee family and also some of the insects that are most easily identified as bees in the world. It includes carpenter bees, both large and small, and their relatives in the subfamily Xylocopinae. The Nomadinae is made up exclusively of cuckoo bees with remarkably diverse adaptations for ovipositing in host brood cells. The flower bees, Anthophorinae, are often bumble bee–like but, unlike bumble bees, they are solitary. The Eucerinae includes the long-horned bees and their relatives. Lastly, the Apinae includes all the so-called “corbiculate bees”—the orchid bees, bumble bees, honey bees, and stingless bees—as well as a couple of genera of mostly oil-collecting species. The honey bees and stingless bees have perennial colonies, whereas bumble bees (except the socially parasitic ones) have annual societies. All these subfamilies are found almost wherever there are flowers.

As long-tongued bees, all Apidae are expected to have the last two segments of the labial palp very short compared to the first two and at right angles to them. But there are two lineages that have lost this otherwise defining characteristic: the oil bees of the genus Ctenoplectra; and the genus Ancyla, species of which do not need a long tongue because the flowers they visit are umbellifers (such as carrot flowers) and are so small that the nectar is easy to reach.

See also Body Plan; Classification; Corbicula; Eusocial; Mouthparts; Scopal Hairs; Social Parasitism.

Apis

Apis is the genus name for honey bees, which includes Apis mellifera—the domesticated western honey bee. That long common name is necessitated by the fact that a second species—Apis cerana, the eastern honey bee—has been domesticated in Asia, but even there the western species is also used.

There are perhaps a dozen species in the genus Apis and it is somewhat surprising that the taxonomy of such important bees remains controversial. One species was described as recently as 2023—from southern India, though its taxonomic status requires further study. Overall, the genus can be divided into three groups based partly on size. The giant honey bees (sometimes placed in their own subgenus—Megapis) are the Asian Apis dorsata and its relatives. At the other extreme are the dwarf honey bees (subgenus Micrapis), small species that are largely restricted to tropical Asia but also found on the Arabian Peninsula and Eastern Africa. Both the giant and the dwarf honey bees build nests in the open, on tree branches or outsides of buildings and their nests are covered by the bodies of workers. It is only the medium-sized group of honey bee species, like the eastern and western domesticated ones, that make hives inside a cavity—originally a naturally occurring cavity such as a hollow log or tree trunk.

The domesticated western honey bee has been taken worldwide for honey and wax production and pollination.

See also Apidae; Clan Apis; Eusocial; Wax.

Beetles as Natural Enemies of Bees

Many beetles are natural enemies of bees, with some being generalist predators that will include bees as well as other insects in their diets while others have very specialized relationships with particular bee lineages. Most oil beetles, family Meloidae, are enemies of bees: their active first instar larvae, called triungulins, find their way into a bee nest where they will consume the larvae and food provisions. Some triungulins gain entrance by smelling like a female bee and attracting a male. The beetle larva then transfers to a female bee when she mates and is then taken back to the host nest.

Ripiphoridae, or wedge-shaped beetles, also have active first instar larvae. Their first instar larvae produce an adhesive that enables them to stick to the body of their host and, unlike most enemies that hitch a ride on their host, they are often found on bee wings. Once the larva gets into the nest it searches for a bee larva that it penetrates and stays inside without feeding until the host is fully grown.

Hive beetles are pests of honey bee colonies. There are two groups of concern, the small hive beetles (of the family Nitidulidae) and the large hive beetles (in the family Scarabaeidae). While the latter has not spread far beyond its native African range, the former is now a pest on multiple continents in addition to its native Africa. Small hive beetle larvae eat stored nectar and pollen, making a mess of the brood comb and defecating in the honey! Large hive beetle larvae eat bee brood.

See also Flies as Natural Enemies of Bees; Stylopids; Wasps as Natural Enemies of Bees.

Biogeography

Biogeography is the study of where different groups of organisms are found and how they got there. The modern approach to the subject involves obtaining a calibrated phylogeny—an evolutionary tree where the origins of different branches have an approximate date associated with them. This requires a molecular phylogeny, fossils, and a morphological phylogeny to show where the fossils would be placed in the molecular phylogeny. The regions where different groups are found are then mapped onto the phylogeny to reveal changes in distribution. The timing of the changes in distribution can then be interpreted in terms of geological events and paleoenvironmental conditions.

Using these approaches, the earlier idea that bees originated in somewhat arid areas in the southern hemisphere has been demonstrated as likely to be true. Some lineages seem to have been restricted to particular southern continents for some time (e.g., Melittinae in Africa) but moved northward under favorable climatic conditions, while others remain associated with single southern continents (e.g., Meganomiinae, also in Africa). The opening up of the Atlantic Ocean separated some bee lineages into western and eastern hemispheres. But subsequent movements from the western to the eastern hemisphere, and vice versa, occurred over transatlantic and Bering land bridges and the estimated dates associated with movements of such lineages generally agree well with when these bridges were above water.

Bees were impacted by periods of warmer and colder climatic conditions. Warmer conditions allowed bees adapted to tropical conditions to move northward and southward into what are now temperate regions, but as colder temperatures returned, eventually their ranges contracted to the present-day tropics. These climatic fluctuations enabled the stingless bees, currently restricted to the tropics, to get at least as far north as New Jersey during past warmer periods.

See also Endemic; Xeric Environments.

Body Plan

As with most winged insects, bees have a head, a thorax that bears two pairs of wings and three pairs of legs, as well as an abdomen that houses, among other things, the reproductive organs. As with all other Hymenoptera except the sawflies, bees have a narrow waist that looks as if it is between the thorax and abdomen but is actually between the first and second abdominal segments. Thus, what appears to be the thorax is the real thorax plus the first abdominal segment and what appears to be the abdomen is the abdomen minus the first abdominal segment. The middle and hind parts of the body are called the mesosoma and metasoma, respectively, and these terms are used throughout this book.

Thus, bee bodies are divided into three major parts: head, mesosoma, and metasoma. The head bears the mouthparts, antennae, compound eyes, and ocelli. The latter are three small discs, situated near the top of the head, that function to measure light intensity. The mesosoma has three thoracic segments plus the propodeum—the part that in earlier evolutionary phases was part of the first abdominal segment. The first three of these have legs and the second and third have wings. The metasoma has six segments visible from the outside in females and seven in males; there are additional segments that are telescoped within the metasoma. These form parts of the sting apparatus in females and the terminalia in males.

For other entries in this book, it is useful to know that each external metasomal segment is clearly divided into a dorsal tergum (plural: terga) and ventral sternum (plural: sterna).

See also Antennae; Mating; Mouthparts; Sting; Terminalia.

Body Size

Bees vary in length from less than 2 millimeters to 4 centimeters. The record for the smallest bee is shared between two very different types of bee: Perdita minima—an andrenid—and several species of stingless bee. The former nest in the ground while the latter are social bees with a few hundred individuals in a small nest. Which bee is the largest depends on how you define large. The longest bee is Wallace’s giant resin bee—Megachile pluto. It is so long partly due to its enormous mandibles, which it uses to collect resin to construct its brood cells inside the nests of arboreal termites. The heaviest bees are some bumble bee queens and some large carpenter bees.

Body size is an important ecological trait with numerous ramifications. For example, small bees foraging on large flowers might be able to collect all the pollen they need by landing directly on the anther without ever touching the stigma: they may not pollinate. Small bees are also potentially limited in the depth of nectary from which they can obtain nectar, although even some of the smallest bees have remarkably long tongues.

In general, the larger a bee is, the further it can forage for resources. The record for long distance flights is probably held by an Indian large carpenter bee that flew 18 kilometers to its preferred flowers. At the opposite extreme, it has been suggested that a single eucalyptus tree might host an entire population of some tiny Australian euryglossine bees with each tree having its own population of these bees nesting nearby.

See also Central Place Foraging; Pollination.

Brood Cell

The brood cell is where most bees spend their youth, developing from egg to adult, perhaps best known from honey bees, where the hexagonal brood cells in honeycomb are used both for offspring development and honey storage. Brood cells take on a wide range of shapes and orientations depending upon the nesting substrate and the type of bee that makes them. Ground-nesting bee brood cells are typically somewhat longitudinally oval and round in cross section. There is usually a short neck between the brood cell and the burrow that it opens into, or the brood cell may be placed at the end of a lateral branch of variable length. While they are typically somewhat horizontal in orientation, some bees construct vertical brood cells. Waxy brood cell linings are secreted by most ground-nesting bees and serve to maintain humidity within the brood cell and keep out excess water. Some bees provide no waxy lining while still others coat the pollen ball with a hygrophobic layer rather than lining the brood cell.

Bees nesting in narrow, pithy stems or in beetle burrows in wood have cylindrical brood cells, usually placed end to end. Masked and leafcutting bees and their relatives are the most common bees using such substrates and they line the brood cells with polyester-like substances or extraneous material such as pieces of leaves, petals, or resin, respectively. Similar materials separate individual brood cells, though a few bees do not make partitions, either having one large provision mass into which multiple eggs are laid (some Fideliinae in the Megachilidae) or a crèche of offspring of various ages at the end of a tunnel (some Allodapini belonging to the Apidae).

Brood cells are usually closed, except in situations where the larvae are fed progressively. Though in some species, even closed brood cells will occasionally be opened and inspected by the mother.

See also Provisioning.

Bugonia

In some areas around the Mediterranean, there was an ancient ritual aimed at remedying a lack of bees. One version of it involved beating a healthy ox to death in a manner that resulted in it being terribly mutilated but preferably with no loss of blood. The ritual took place inside a sealed house built to precise specifications. The ox’s body openings were plugged with cloth soaked in pitch. The doors and windows of the house were then closed and covered in clay to make the house as hermetically sealed as possible. Three weeks later, the house would be opened and then, eleven days after that, it was expected to be full of bees.

This seems to be a rather extreme (and extremely unpleasant) way to improve honey production and / or pollination. But it also seems likely to have been based on a misidentification: surely the insects found inside the house where the ox would have rotted would be flies, or perhaps meat-eating wasps.

Despite the dubious nature of the claim of bees arising from carrion, the phenomenon is mentioned in ancient texts from multiple cultures, in religious texts (including the Bible), Shakespeare, and, more recently, in the Outlander series.

There is a story in Hindu mythology that has some similarity to bugonia: the goddess Parvati killed a demon by stinging him to death aided by large numbers of black bees that emerge from her body.

See also Religion.

Bumble Bees

With their long, dense, brightly patterned clothing of hair, bumble bees are among the most charismatic of the microfauna and among the most easily recognized bees. They are found throughout suitable habitats in the northern and western hemispheres but are absent from sub-Saharan Africa and Australia except as introduced populations. Bumble bees reach a higher altitude and latitude than any other bees, being found over 5,000 meters up in the Himalayas and at 75° North on Ellesmere Island. Their dense covering of hair, combined with body-warming shivering of the flight muscles means that they can warm up more easily in cold climates than other bees can.

Most of the almost three hundred species of bumble bee are eusocial, while approximately 10 percent of them are social parasites that invade the nests of other bumble bees. Nests of eusocial species are initiated in spring by single foundress females, often using an abandoned rodent burrow or similar suitable cavity. The female lays a clutch of around half a dozen eggs, which she feeds progressively with a mixture of pollen and nectar. Once this brood of worker females emerges, they perform the foraging and nest building activities while their mother queen lays all the eggs … for a while. At some point in the summer, the colony switches from producing more workers to producing males and the next generation of reproductive females. At this point, intense competition arises among the workers, and between them and the queen, over who will lay the eggs. Regicide, siblicide, and infanticide (in this case, killing of eggs, larvae, and pupae, or at least their expulsion from the colony where death inevitably follows) occurs as individuals seek to attain dominance.

See also Eusocial; Man vs. Bee; Mimicry; Social Parasitism.

Buzz Pollination

If you listen carefully around a patch of blueberry flowers you might hear high-pitched whining in short bursts. This noise is made by female bees obtaining pollen by buzzing. Buzzing is necessary to effect blueberry pollination because these plants keep their pollen hidden inside the anthers, rather than on the outside, and it must be shaken out through tiny apical pores. Greenhouse tomato growers purchase colonies of bumble bees to pollinate their buzz-pollinated crop and they can assess the success of their pollinators by looking for “bee kisses”: brown marks on the anthers—this is where the bees hold the flower with their mandibles giving them sufficient purchase to let them buzz freely. The buzzing itself is caused by rapid contractions of the bee’s indirect flight muscles, which produce vibrations that shake the pollen out from inside the anthers. The outpouring of pollen can be quite dramatic, resembling a cloud or waterfall. Many bees that buzz pollinate have especially furry bodies to catch the pollen that jets from the flower. Buzz pollination has evolved in many bee lineages and the requirement for buzz pollination has similarly arisen in many plant lineages.

With insufficient bees, buzz pollination can be replaced by the use of electric toothbrushes or similar vibrating tools, although the time and effort it takes makes the use of commercially available bumble bee colonies more attractive. Let the bees do the work!

See also Agriculture; Bumble Bees; Pollination.

Carpenter Bees

There are two related groups of bees that are commonly referred to as carpenter bees: large carpenter bees of the genus Xylocopa and small carpenter bees of the genus Ceratina. The former usually nest in woody substrates such as old logs, furniture, and wooden sidings, often becoming pests as a result. The latter generally nest in smaller pithy stems such as raspberry canes or old sumac stems. Both genera belong within the Xylocopinae, a subfamily of Apidae that also contains reed bees, a genus of oil bees, and a few additional genera.

Both groups of carpenter bees have simple forms of social behavior in at least some of their members. Xylocopa daughters often stay in the nest with their mother while she forages to produce additional offspring in the second year of her life. Sometimes the co-occupants aren’t related. These additional females are “hoping” to take over the nest when the mother dies—after all, chewing so much wood to create a brood tunnel is an enormous amount of work that might best be avoided. Ceratina mothers of some species produce a small daughter as the first offspring in the nest. This dwarf eldest daughter (or DED!) then forages late in the year to provide food for her adult siblings to increase their chances of overwintering but at the cost of reducing her own survivorship.

A 2023 paper indicated that solitary behavior was ancestral to the subfamily Xylocopinae with the evolution of facultative sociality multiple times and obligate sociality twice. However, reversals to solitary behavior also occurred on multiple occasions.

See also Body Size; Eusocial; Snapping.

Cartoon Bees

Bees have been the topic of cartoons and cartoonish illustrations for a very long time though they have become more popular recently, perhaps because of increasing concern about declines in bee populations. But almost all these representations are woefully inaccurate. Certainly, anthropomorphic modifications of eyes and mouths might be expected, but almost all cartoon renditions of bees show no sign of the narrow waist, there are often only four legs (often with the hind pair close to the tail end), sometimes only two wings, and, in cartoons aimed at scaring the viewer, a massive, permanently extruded sting. Alas, many cartoon bees are males—for example, Barry B. Benson from the 2007 Bee Movie (voiced by Jerry Seinfeld!), who often behaves in a manner typically known only in females.

Perhaps the earliest cartoon bee was in the 1912 book The Adventures of Maya the Honeybee, which was turned into a series in Japan in 1975. Another series with a similar title—The Adventures of Hutch the Honeybee—involves a male bee attempting to find his mother after their hive is destroyed by hornets. The second Hutch series involved Hutch and his sister Aya rebuilding their hive, with Aya becoming the new queen. While it is nice to see males helping females with household tasks, this is an anthropomorphism and honey bee males are, justifiably, called drones.

Perhaps the most famous cartoon that includes bees is Winnie-the-Pooh. Pooh loves honey but the colonies the bear attacks for a sweet reward are clearly wasp nests: no bees build large nests that hang down from a narrow pedicel.

Of course, most bee cartoons concern honey bees or bumble bees, but those of the Polish entomologist Justyna Kierat concern a much greater diversity of species.

See also Clan Apis.

Cavity-Nesting

This is a broad term referring to bees that use above-ground hollow features as the site to build their nests. Some do the “hollowing” themselves and are called excavators, others rent a cavity constructed by another organism. The range of locations used include stethoscopes (irritating to doctors in a field hospital), fuel lines of crashed aircraft, patio furniture, padlock keyholes, abandoned organ-pipe wasp nests, snail shells, and more standard items such as holes or cracks in walls or abandoned beetle burrows in wood. Excavators construct the cavity by, for example, chewing into a pithy stem. Excavators need to find a suitable substrate and these can be augmented for bee conservation by snapping old raspberry canes or stems of other suitable plants, so the pithy interior is clearly exposed. Some Australian bees prefer to excavate nests in the dead flowering stalks of grass trees, often using those where an emu has bitten off the inflorescence. Some renters are remarkably choosy in the nature of the cavity they will use. One European species of masked bee, Hylaeus pectoralis, nests only in the vacated galls made by a fly species (Lipara lucens, Chloropidae) on rush stems, and numerous bees will only nest in empty snail shells. Other renters are far less particular. As appropriate cavities are often in short supply (in comparison to soil), some bees lower their threshold for an acceptable cavity to a mere depression in the surface of a rock.

See also Nesting Sites; Snapping.

Central Place Foraging

Bee females (other than cuckoos and socially parasitic species) construct a nest and bring back food to it. The nest is where they lay their eggs, and although there are a few species that are known to use a different nest site for each pollen ball and egg (including Perdita minima, the smallest bee), most will do all their egg-laying in one nest. This is quite different to the reproductive behavior of nearly all other insects whose females fly around laying eggs in appropriate places as they go, never having to return to the same place. In contrast, bees are central place foragers, returning to their nest time and time again to bring back the food needed for the next generation.

There are numerous ramifications of this ecological trait. First, bees must remember the location of their nest. At close range this is achieved through orientation flights and, in some species at least, their sense of smell. Over longer distances, bees seem to record the pattern of the horizon as they fly away from the nest and then observe the pattern in reverse to find their way home. Second, different populations of a bee species may be more isolated than those for which there is no home to return to and where each offspring may be produced at some distance from any other. This suggests that bees may have greater difficulty dispersing over long distances compared to other insects.

See also Nesting Sites; Orientation Flights.

Citizen Science

The number of professional scientists is quite small and it is difficult to impossible to study bees (or other organisms) at multiple locations across the planet at the same time. This is where citizen scientists can be especially helpful. Citizens are, by definition, all over the populated globe and can also travel to the most remote of places. With relatively brief training, it is possible to learn to identify species in particular groups. Plants, birds, and butterflies are relatively easily identified through guidebooks and many citizen science programs have involved them. For bees, it is mostly bumble bees that have received the attention of citizen scientists, although a wider range of identifications of bees (and other organisms) from throughout the world is possible through the online platform iNaturalist.

Bumble Bee Watch is a North American program where citizens take a photograph of a bumble bee, log in to their account and post the image online, provide an identification using online tools and then have that identification confirmed or corrected by experts. The resulting database has been used in prestigious scientific publications. Citizen scientists can even contribute to our understanding of the more obscure and difficult to identify species by taking a good quality photograph and submitting it to a website. iNaturalist is one such site where hundreds of thousands of bee records have been validated by experts providing reams of information to be added to our geographic databases of bee occurrences and understanding of their biogeography.

See also Biogeography; Databases.

Clan Apis

Clan Apis is a graphic novel written by Jay Hosler, a Professor of Biology at Juniata College in Pennsylvania. Having been a postdoctoral fellow at the Rothenbuhler honey bee research laboratory at Ohio State University, he is well versed in the science of the topic. Unsurprisingly, given this background, Clan Apis gives a good depiction of life in a honey bee colony and the drawings are also accurate (though often with too many antennal “segments” and unsurprisingly anthropomorphized bee larvae). Starting with the origin of the universe initiated by a flower in the “big bloom,” it follows a worker—accurately a female, called Nyuki (which is Swahili for bee). After the big bloom, Nyuki first appears as a fully grown larva whose brood cell is about to be capped by her older sister (Dvorah, Hebrew for bee). The book then follows Nyuki as she metamorphoses and then goes through the various tasks that worker honey bees perform over their lives.

Released in 1991, it was Hosler’s first full-length graphic novel, followed by four since then, one of which was funded by the National Science Foundation. His first forays into comic strips were while he was an undergraduate, and while a graduate student he was paid to write a daily comic for the student newspaper.

See also Antennae; Apis; Cartoon Bees.

Classification

Biologists use the hierarchical method of classifying organisms developed by Carl Linnaeus in the 1730s. Thus, bees are Animalia within the phylum Arthropoda, Class Insecta, Order Hymenoptera, and superfamily Apoidea. They share their superfamily with a number of families of wasps—termed “apoid wasps” to differentiate them from the parasitic wasps, yellowjackets, hornets, and so on, which, although they are Hymenoptera, belong to different superfamilies. The number of apoid wasp families is in flux as our understanding of their phylogenetic relationships changes but most melittologists accept seven families for the bees. These are the Andrenidae, Apidae, Colletidae, Halictidae, Megachilidae, Melittidae and Stenotritidae. A few melittologists put all bees into a single family (which would be called Apidae). All named groups within the Linnean hierarchy are expected to be monophyletic: they should contain the common ancestor and all of its descendants. Thus, the original member of the Megachilidae is expected to share the long-tongued mouthpart morphology of all long-tongued bees and the labrum broadest at the base—these two features in combination help define the family and though the former is shared with the Apidae, bees in that family have a labrum that is at least somewhat narrowed toward the base.

Families are then further divided into subfamilies, tribes, genera, and subgenera (there are more levels than this—after all, it is impossible to flatten a tree with millions of twigs into a linear classification, but these are the most commonly used levels). The constitution of many of these groups changes as our understanding of the evolutionary history of a group expands. The appendix gives an outline classification of the bees such that all species or genera named in this work can be placed within their evolutionary context. This classification differs from one that might have been used only a few years ago, however, and is likely to change in the future.

See also Biogeography; Monophyletic; Mouthparts.

Cockerell

Theodore Dru Alison Cockerell (1866–1948) is well known to melittologists because he described more species of bee than anyone else has. He was employed as a museum curator and university teacher and his somewhat peripatetic career helped his bee research as he worked in several institutions in the southwestern United States—a part of the world that has more bee species than any other of comparable size. He also collaborated with researchers worldwide and travelled widely to collect specimens himself, often accompanied by his wife Wilmatte Cockerell (née Porter). He named bee species after her, both before and after they married—examples being the wool carder bee Anthidium porterae and the bumble bee Bombus wilmattae.

Cockerell did not limit himself to the study of bees, or even just to insects. Indeed, he provided new names in most groups of organisms, including plants (over three hundred), mammals (three), arachnids, and molluscs: the first species he named after Wilmatte was a sea slug, albeit a beautiful one. With over seven thousand species named, he may have described more species than anyone else other than Linnaeus. But he is best known for his work on bees, for which he coined over five thousand names, not all of which remain valid. Given that he published literally thousands of research articles starting as a teenager, it is not surprising that many of them were extremely short and lacking in detail, a practice that continues among some melittologists to this day.

Like many people who spend their lives studying the minutiae of life, Cockerell had some unusual personal quirks. One of these was his penchant for not wearing socks.

See also Michener; New Species; Urban.

Cocoons

Many insects with complete metamorphosis construct cocoons. They are made by the fully grown larva, and metamorphosis to the adult stage occurs within the cocoon. While cocoon construction is ancestral in bees, it has been lost independently many times during their diversification. Whether a bee larva makes a cocoon or not is usually taxonomically restricted. For example, within the Colletidae, all Diphaglossinae construct cocoons, whereas elsewhere within the family only one other species is known to do so. However, some bees in the Eucerinae will construct a cocoon only if the individual is to overwinter and not if it becomes an adult in the same year.

Cocoons protect against disadvantageous weather conditions—for example, in arid environments, they aid in preventing desiccation. Other functions include protection against parasites and pathogens and, in cases such as cuckoo bees of the genus Stelis (Megachilidae), they resist the strong mandibles of the hosts that emerge from deeper in the nest tunnel.

Bee larvae make silk for their cocoons from their salivary glands, and the salivary openings of the labium are wider in groups that make cocoons than in those that do not. Considerable resources are expended in making the cocoon; almost half the body weight of the adult that emerges may have been expended in cocoon construction. This results in adult bees that are smaller than might be expected given the size of their larvae.

Cocoons are usually constructed after or during defecation; if during defecation then sometimes the feces are incorporated into the structure of the cocoon. Cocoons are usually oval but often with a complex nipple-shaped structure at the “head” end that permits gas exchange while still restricting enemy access.

See also Larva; Phenology; Pupae.

Colletidae

The Colletidae is a diverse family comprising bees of all phenotypes from tiny almost hairless bees to large bumble bee–like species. Except for males of a few species, they all share the common characteristic of having a glossa that is concave at the apex. The concavity ranges from being very shallow but on a very wide glossa, as in the Euryglossinae, to being deeply bifid, as in most Diphaglossinae. Another characteristic of this family is that they line their brood cells with a cellophane-like substance. This is produced by a gland inside the metasoma, the liquid is released through its apex and painted onto the brood cell walls using the glossa as a paintbrush. The brood cell linings can be quite complex, with up to three layers, sometimes with silk added to other glandular secretions, and they serve to waterproof the brood cell. This waterproofing can serve both to keep water out as well as to maintain humidity within and it enables colletids to construct an unusually liquid provision mass for their offspring.

Classification of Colletidae has changed several times in recent years and is still in some flux. Currently, perhaps eight subfamilies are accepted. The Euryglossinae and Callomelittinae are restricted to Australia; the Scrapterinae are found only in Africa (almost exclusively in southern Africa); the Diphaglossinae are found from the southern United States to southern South America with one genus in Australia; the Xeromelissinae are primarily South American; while the Neopasiphaeinae (surely the ugliest subfamily name among all bees) are found mostly in South America and Australia. Colletinae are found on all continents except Australasia and Antarctica, whereas the Hylaeinae are worldwide except for Antarctica.

See also Brood Cell; Classification; Mouthparts.

Communal

Most bees are solitary, with a single female occupying each nest. Some have queens and workers. But there are also bees that live in groups in an egalitarian fashion: they share a nest entrance but otherwise act as if they were solitary. In these communal nests, each female constructs her own brood cells, collects food for her own offspring and lays her own eggs. Communal behavior has arisen independently multiple times among the bees and communal societies may range in size from just two individuals to hundreds. Some of the largest communal groups have been found in a Brazilian species of Exomalopsis in which there were hundreds of females sharing a nest entrance and the nest had been occupied for multiple generations. Perhaps unsurprisingly for such an old and populous nest, it was also extremely deep. Other large communal societies have been found in some species of Andrena (suggesting that their oft-used common name “solitary mining bees” might not always be appropriate), some of their relatives in the Panurginae, and in some Australian Lasioglossum species.

An advantage of living in a communal society is that the nests are more difficult for intruders to access because there is more traffic at the nest entrance and more bees to detect an invader once it has entered. Perhaps a disadvantage is that it is more difficult for individuals to control cheaters—individuals that stay within the nest and lay eggs on pollen balls constructed by others.

A corollary of communal nesting is that males that emerge within one are surrounded by mating opportunities. This has resulted in some communal bee lineages evolving an aggressive male morphology.

See also Agapostemon; Dimorphic Males; Eusocial.

Corbicula

Corbiculae are a special kind of pollen transport structure defined as a bare area surrounded by hairs that hold the pollen in place. It is best developed in the appropriately named “corbiculate bees”: the orchid, bumble, honey and stingless bees. In most species in these groups, the hind tibia is largely concave and bare on the anterior surface while the dorsal and ventral margins possess curved hairs that help hold a pellet of pollen in place. These bees moisten the pollen with nectar and this helps ensure that pollen is not lost during transportation. But it is not only in the “corbiculate bees” that corbiculae can be found, and they are not only found on the metatibia. The mining bee genus Andrena have a propodeal corbicula—long curved hairs that surround the lateral surface of the last portion of the mesosoma, as well as a femoral one. Most colletids of the subfamily Xeromelissinae have a corbicula on their second metasomal sternum where dense, posteroventrally oriented hairs surround a triangular bare area. Many bees that transport pollen on their hind legs have the ventral surface of the femur bald but surrounded by hair fringes that extend ventrally from both the anterior and posterior surfaces and, in Andrena, also basally from the trochanter. The Argentinean eucerine Canephorula apiformis is unusual in that the apical half of the hind tibia forms a corbicula whereas the basal half is entirely covered in hair.

See also Apidae; Pollen Acquisition.

Cuckoo Bees

Just like their avian namesakes, cuckoo bees do not make their own nests and do not collect food for their offspring. Instead, they lay eggs in the nests of other species and their offspring feed on the resources collected by the hosts. The switch from nest-building and food-collecting to cuckoo behavior (also called brood parasitism or clepto- or kleptoparasitism) has occurred multiple times among the bees—indeed, it has arisen multiple times in each of the three bee families in which it is found: Apidae, Halictidae, and Megachilidae.

Females of most cuckoo bees lay their egg in the brood cell while the host is out foraging. You can often see them flying around the surface of the ground (most, but not all, attack ground-nesting bees) searching for a host nest entrance. Sometimes, however, the host will come home to discover their enemy at work and so cuckoo bees are generally rather well defended, often with long stings, dagger-like mandibles, and a thick integument with lots of pits and ridges to deflect weapons away from the more vulnerable body parts. It is a safer bet to enter a nest when the host female has finished it. This often requires more elaborate brood cell opening and resealing behaviors but has the advantage that the host is not likely to discover the invader.

Cuckoo bee females have to place their eggs carefully to make it less likely that the host will discover them. Cuckoo bee eggs are thus often diverse in structure compared to the simple banana-shape of other bee eggs. Egg-hiding is less important if the cuckoo attacks only completed nests.

See also Hospicidal; Ovaries, Ovarioles, and Oocytes; Social Parasitism.

Databases

It is becoming increasingly important to make the information from specimen holdings in museums widely available in the form of online databases. One reason is that it’s not just biodiversity that is at risk of extinction; museum specimens themselves have been called “the endangered dead,” because their maintenance is not cheap and there are so many other calls for financial assistance for research. But the information that has until recently been locked away in dusty cabinets is proving extremely important for understanding many issues, including the impact of climate change on the planet’s most important pollinators.

Because museum collections go back for decades and even centuries, they can help document changing geographic distributions of species over time. Such studies have documented serious declines in some species and resulted in some bees being placed on national endangered species lists. One such study suggested why some bumble bee species are becoming threatened with extinction: while the southern distribution margins of northern hemisphere species were retracting northward, this was not compensated for by northward expansion at the northern edge of their ranges. The result is a decreased geographic range. That historical bee distribution records accurately track changing climate can be demonstrated by using old records of both bees and climate to predict where the species should be found now. Close agreement between predicted and observed current distributions suggests that the future distributions of the bees can be predicted under different scenarios of climate change with some accuracy.

Databases for wider ranges of bee species have demonstrated the unusual global pattern of bee species richness. There are more species in temperate zone deserts and semi-arid areas than in the tropics, a pattern that is unusual as most taxonomic groups show greatest diversity in the tropics.

See also Biogeography; Citizen Science.

Defecation

Both larval and adult bees have to defecate. The larvae are particularly interesting in how they achieve this because in most cases they store up all the waste from the food they consume during their growth and do not defecate until they have eaten it all. Thus, they avoid fouling their food. Indeed, in bees—as in the other Aculeata and Parasitica, the midgut doesn’t even unite with the hindgut to permit defecation until late in larval growth. Before defecation, the fully grown larva is shiny because its skin is so stretched. As it starts to defecate it deflates somewhat, looking older and more wrinkly. Some bee larvae use their feces to line their brood cell, sometimes eating sand to make a tough, cement-like lining.

Adult bees have to defecate soon after emerging from the pupa as the waste resulting from all the metabolic activity of metamorphosis has to be expelled.

Honey bees can use mass worker defecation as a colony cooling mechanism. In 1981, the United States claimed that Russia had supplied the combatants in tropical Asia with mycotoxins that were detected in what was called “yellow rain.” It turned out to just be honey bees defecating en masse to cool down their colony in the tropical heat. The “yellow rain” contained large amounts of digested pollen grains. Despite the scientific evidence, the United States has still not retracted the accusations.

See also Cocoon; Larva.

Digging

Studying bees that nest in the ground is not straightforward. Typically, to find out what the bee’s nest architecture is like, what its egg, larva, pupa, and cocoon (if it makes one) look like, or even to count the number of chromosomes it has—the researcher has to dig the nest up. This is easy if the nest is very shallow but can be very difficult indeed if there are numerous branches or diversions around tree roots or subsurface rocks. Some bee nests are so deep that the researcher must dig steps into walls of the hole they have dug to get out! Of course, the smaller the bee, the narrower the burrow and the more likely that the researcher will lose the plot.

Different melittologists use different techniques to get data from burrowing bees. Some make a liquid slurry of plaster of paris that they squirt down the nest entrance. When hardened, this makes tracing the structure of the nest and finding all of its contents relatively easy. Others blow talcum powder down the nest entrance and then dig down perhaps using a grass blade to help follow the burrow. When bees nest in dense aggregations, it is impossible not to cut into multiple nests at a time. Both of these previous methods can be adapted by using multiple colors of powder whether in liquid or dry form. Still another approach is to plug the entrance, dig a “moat” around the nest and then coat the outside of the block of soil with linen soaked in plaster of paris. When dry, the whole block can be transported back to the laboratory to be dissected from the comfort of a laboratory chair.

See also Aggregation; Brood Cell; Nesting Sites; Snapping.

Dimorphic Males

In some bee species, the males come in two different size classes: small, normal-looking individuals and unusually large ones. The smaller males behave like males of most bees—they fly around looking for females on flowers or other rendezvous areas such as shrubs with particularly glossy leaves or around the nest site where virgin females may be emerging. The larger males generally have such disproportionately large heads that in some cases they have been called “walking heads” and may be sufficiently ungainly that they are incapable of flight. These individuals are “built like tanks,” but why? Extreme male dimorphism seemingly occurs only in species that nest communally. Any male emerging within a communal nest has plenty of mating opportunities with the daughters of the other females that provisioned the nest in the previous generation. Thus, their fighting morphology increases their chances of obtaining multiple mates. These big-headed males may never leave their natal nest and battles between them have been observed to go on for hours, often ending fatally for the loser.

Other bees have more continuous variation in size of their males with similar, but not so extreme, strategies. The larger males will fight for mating opportunities, sometimes digging down to where virgin females are emerging while smaller ones try to avoid potentially damaging combat by searching for mating opportunities using more traditional means.

See also Communal; Mating.

Division of Labor

In insect societies, different individuals take on different tasks. The most common and best known is a reproductive division of labor where queens do all, or at least a disproportionate amount, of the egg-laying and little to none of the other tasks, while the workers (who are all female) have little or no direct reproduction but perform all or most of the remaining tasks. In honey bee colonies, this reproductive division of labor is usually complete, with workers laying no eggs unless the queen is lost. Stingless bee workers often lay eggs but these serve a nutritive function and are eaten by the queens. But in most social bees including bumble bees, most social halictines, and some carpenter and reed bees, there is competition over oviposition, especially when it comes to male production. In bumble bees, the competition between workers and queen and among workers can result in the queen’s death and some workers causing the death of the offspring of the queen and / or other workers.

Behavioral differentiation often occurs at finer scales. Most social halictines will have one worker that concentrates on guard duties while some neotropical stingless bees evolved a large soldier caste in response to the evolution of robber bees. Honey bees have specialized undertakers that can detect a dead bee within half an hour and many social bees have “police” that eat eggs laid by rebellious workers.

See also Apis; Eusocial; Meliponini; Robber Bees.

DNA Barcoding

With almost 21,000 described species and some genera containing over 1,000 species, bee identification can be extremely difficult and time-consuming. Even for genera with a few species, it is often difficult to separate the morphological signal that indicates species level differences from the morphological noise that is intraspecific variation. Fortunately, there is an entirely different approach that can help: DNA barcoding. This method, an invention of the Canadian biologist Paul Hebert, uses small pieces of mitochondrial DNA (typically a 658 base pair region of the cytochrome oxidase gene CO1) to identify specimens. Mitochondrial DNA is good for this task in animals because it is inherited only from the mother and does not recombine. As a result, any mutation will be passed down to the offspring and subsequent generations and any further mutations in that lineage will crop up only in combination with the previous one. Thus, differences accrue over time and we usually end up with larger DNA sequence divergence between species than there are within species. There is no absolute rule as to how many differences there must be for two individuals to belong to different species. With 658 base pairs, thirteen differences give an approximately 2 percent divergence, but in some cases sequence divergence between morphologically distinct species can be zero. As always in science, it is best to get as much data as possible, and so integrating morphological with DNA data is often particularly beneficial. Discovery of DNA barcode differences within “one species” often leads to the discovery of morphological differences and the description of new species. Another great advantage of the method is that it helps associate the sexes, which is not always as straightforward as one might imagine, given that most bees are highly sexually dimorphic. DNA barcoding approaches can also be used to discover what species are found in mass samples.

See also Classification; New Species.

Endemic

A taxonomic group that is only found in one geographic area is said to be endemic to that area. While there are numerous species or genera that are endemic to a particular country, geographic region, habitat, or biome, some whole subfamilies are endemic: the Callomelittinae and Euryglossinae are endemic to Australia, the Scrapterinae to Africa, and the Xeromelissinae to South America—with a few species getting into Central America and one into the Antilles.

Endemic groups often arose in the area where they remain restricted. Geographic barriers often preclude their dispersal elsewhere. Australia clearly has oceanic barriers, making it unlikely that bees can easily get to other parts of the world from there. Chile, while having a very long border with adjacent countries, has the hyperarid Atacama Desert to the north, oceans to the south and west, and the Andean peaks to the east, and as a result a large proportion of its bee species are found in no other countries.

When isolated islands are colonized by a bee, they may undergo multiple speciation events there. Examples include Hasinamelissa—a genus of reed bee with twenty-five species all restricted to Madagascar—and the neopasiphaeine Nesocolletes, which is restricted to New Zealand where there are seven species.

See also Biogeography; Databases.

Eusocial

By definition, a eusocial organism has cooperative brood care, overlapping generations, and a reproductive division of labor between parents and offspring. In bees, there are no kings (unlike in termites, but as in ants and yellowjackets): eusocial bee societies generally consist of a queen and her worker daughters. While most bees are solitary, with a single female constructing a nest and brood cells, foraging for resources to construct pollen balls and laying eggs, in eusocial societies the queen does most of the egg-laying and the workers do most of the foraging and other colony tasks.

We can divide eusocial societies into two broad types: those in which there is a solitary phase at the beginning of the colony cycle and those in which there is never a solitary phase. In the latter, new bee colonies are started by a queen and a group of workers, usually by swarming. This type is commonly referred to as “advanced eusocial” and the colonies are usually perennial. Honey bees and stingless bees have this type of eusocial organization. Bumble bees and some halictines have their colony initiated by a single female foundress that starts a nest and produces a brood of workers all by herself. Once the female offspring reach adulthood, they become workers and do the foraging and nest maintenance and guarding tasks, leaving their mother, the queen, to concentrate on egg-laying. With few exceptions, such primitively eusocial colonies last less than a year. While there may be a single brood of workers as in some bumble bees in very cold climates, or cool temperate climate halictines, most bumble bees and some halictines produce workers continually until males and next year’s queens are produced later in the summer.

See also Haplodiploidy; Queen; Worker.

Flies as Natural Enemies of Bees

Many predatory flies will attack adult bees and suck their juices. Prime among these are the robber flies (Asilidae), some populations of which will persist through attacking bees that nest in dense aggregations. Some other flies oviposit in adult bees and their offspring develop within the doomed host. Within the scuttle fly family, Phoridae, there are some that are termed “bee-killing flies,” tiny insects, 2–3 millimeters in length, known only from warmer parts of the western hemisphere. They have two modes of attack—flying at a stationary or flying bee and ovipositing on them or landing near where a bee is resting, curling their ovipositor forward beneath their bodies and running at their victim wielding the ovipositor like a sword. These are specialized behaviors and, as may be expected, work well where large numbers of bee hosts may be found; consequently, these flies mostly attack social species such as stingless bees, honey bees, and bumble bees. The other main group of adult bee-attacking flies are the thick-headed flies, Conopidae. These follow the first of the two tactics of the bee-killing flies and insert a barbed egg into the membrane between the segments of the bee host. Both these types of dipterous enemy develop as larvae inside the body of the adult bee.

Other flies develop on bee larvae or just the food provided for them. Best known among the former are the bee flies, family Bombyliidae, which flick eggs into the nest entrances of their hosts where the larva waits until the host larva is fully grown before attacking. Species of Leucophora, satellite flies of the family Anthomyiidae, will follow female bees returning to the nest and can be seen flying close behind them even as the potential host zigzags in escape maneuvers. The offspring of these flies eat the food that was meant to be eaten by a bee larva.

See also Beetles as Natural Enemies of Bees; Stylopids; Wasps as Natural Enemies of Bees.

Fossil Bees

The fossil record for bees is reasonably good. Indeed, some amber fossils are of such high quality that the specimen can be studied in as much detail as a recently collected one and in much better detail than a recently collected specimen that hasn’t been looked after properly. Amber is the fossilized resin from trees and so it is not surprising that amber fossils often represent bees that collect resins, such as some stingless bees. Compression fossils form in sedimentary deposits and the structures of the original animal are often distorted through flattening. Wings are nice and flat and compression fossils often show their structure remarkably well. As it is often useful, or even necessary, to include characteristics from wing veins to identify a bee specimen, bee wings in compression fossils often allow remarkably accurate placement within bee phylogenies. Such placements allow researchers to anchor parts of a phylogenetic tree to a particular period in geological time allowing inferences on how, when, and where certain groups of bees diversified. However, reassessment of decisions on the precise classification of some fossils often results in changes to their previously accepted placement. Nonetheless, a paper published in 2023 used data from 185 fossils to generate the most comprehensive calibrated phylogeny for bees so far.

Not only the bees themselves may be found in the fossil record, but also their nests, pollen, and natural enemies. However, suggestions of surprisingly ancient bee brood cells from such ichnofossils are generally considered imprecisely identified.

See also Biogeography; Classification.

Guards

Bee nests contain a large number of resources and other organisms, including other individuals of the same bee species, may seek to steal the resources or consume the bee’s developing offspring. Even the nest itself is a valuable resource because of the effort required to construct it. Thus, bees need to defend these resources and one way they do this is by guarding the nest entrance, which is often done by blocking it with their heads. Solitary bees cannot guard their nests while foraging and may close the entrance when they leave. Social bees often post a single guard at the nest entrance and this individual will try to prevent the entry of natural enemies and unrelated individuals of the same species.

A guard of a social bee should only let her nestmates into the nest. But how do they tell nestmates from other individuals? A series of elegant experiments conducted in the 1970s raised bees with different parentage within the same nest and then investigated whether the guards let in their own relatives that had been raised in other nests or individuals that were close relatives of their nestmates that had also been raised in different nests. The results showed that the bees learned the odors of their nestmates and let similarly smelling bees into the nest but refused entry to their own relatives that had been raised elsewhere. Thus, it seems that the guards do not smell themselves to compare their own odors to those of bees trying to get into their nests, but they memorize the odors of their nestmates and let those that smell like them in while refusing access to their own genetic relatives.

The stingless bee Tetragonisca angustula stations hovering guards outside the nest entrance as well as additional guards that remain around the entrance. If a robber bee is detected prospecting for a nest to invade, the guards attack it. They also attack larger groups of marauding robber bees recruited to the fray.

See also Cuckoo Bees; Eusocial.

Hairs

It is the nature of the hairs on a bee that helps define them as bees: they have branched hairs somewhere on their bodies, whereas wasp hairs lack branches. Unfortunately, there are exceptions. Some velvet ants (a group of wasps with wingless females) also have branched hairs. Conversely, and somewhat irritatingly, it may take a long time to find branched hairs among the simple hairs on a bee’s body.

The pattern of branches on a bee hair is endlessly variable. Some might have a single branch, others multiple branches but only on one side of the shaft, while some have branches on opposite sides of the shaft like a bird feather, and still others have branches coming out in all directions like a Christmas tree. Some hairs are very long, others very short, and hairs of any length can be fine or thick. Short, thick hairs can look like scales and are particularly common lying flat on the body surface of some groups of cuckoo bees. Longer, thick hairs may look like spines or be modified into special structures to scrape open the oil-containing cells of some plants. Most bees have a wide range of different hair types on their bodies, even on the same body part. Some oil collecting bees have a scopa comprised of fine, feathery hairs with long branches as well as long, thick, simple ones mixed among them. The latter give structural integrity to what is really a mop aiding in the retention of oily liquid.

Two ideas have been put forward to explain the origin of branched hairs in bees: either they aid in trapping pollen for transport, or they serve to prevent tiny particles of nesting substrate from lodging between the different parts of the exoskeleton.

See also Corbicula; Oil Bees; Pollen Acquisition; Scopal Hairs.

Halictidae

The Halictidae is a diverse group of mostly small to moderate sized bees. Possession of a basal vein that is strongly curved toward its base diagnoses most members of the family, but as always there are exceptions. There are four subfamilies. Rophitinae is a small group of mostly oligolectic and largely northern hemisphere bees. The Nomiinae are generally larger often with remarkably elaborate secondary sexual characteristics in males with an almost worldwide distribution. The Nomioidinae is a small group of small bees from the warmer parts of the eastern hemisphere. Most Halictidae belong to the Halictinae, and one of its genera—Lasioglossum—has almost 1,900 species, more than any other bee genus, and is found in all areas of the globe that are not covered in ice. This genus has been called “the bane of taxonomists” and “morphologically monotonous” and it is impossible to identify most of its species in many parts of the world, though considerable progress has been made recently by a few dedicated melittologists who like a challenge.

Halictids have the broadest range of social behavior of any group of bees; just the genus Lasioglossum contains almost all named categories of social organization (and cleptoparasitism and social parasitism as well). While many species are solitary, some have queens and workers that are so different, they look as if they belong to different species. Others have relatively large colonies with minimal externally visible differences between castes (dissect them and you’ll find the queen has better developed ovaries than do the workers), which might differ only slightly in average size. One species has colonies that last five years and its queens live longer than do honey bee queens.

A common name often applied to some halictids is “sweat bee,” because they often land on exposed human skin to obtain nutrients.

See also Alkali Bee; Classification; Oligolectic; Social Parasitism.

Haplodiploidy

Bees and other Hymenoptera have a different mechanism for determining the sex of an individual than do most other organisms: males are haploid—resulting from unfertilized eggs—and females are diploid. That is a slight oversimplification, however. The details are that in bees there is a single gene locus that determines sex: if an individual is heterozygous at that locus, then it is a female. But if there is only one type of sex allele at the locus then that individual is a male. If an egg is not fertilized, then there can be only one sex allele and the egg becomes a haploid male. But if a female bee mates with a male that shares one of her two sex alleles, half of her diploid offspring will be homozygous at the sex locus and will become diploid males. Such males seem to be a drain on the population as they may be sterile, produce triploid offspring, or simply not survive long enough to reproduce.

There are additional ramifications of this unusual sex-determining mechanism. First, females can produce male offspring without having mated. Second, a mated female can decide whether to produce a haploid or a diploid offspring and only pass sperm over the egg as it passes through her reproductive tract if the objective is to produce a female. In eusocial bees, this permits the production of broods containing only worker daughters, rather than males. Additionally, as males are commonly smaller than females (exceptions include species in which males are aggressively territorial), a mass provisioning mother can modify her decision as to which sex to produce based on the amount of food available at the time she lays the egg.

See also Eusocial; Kin Selection; Provisioning.

Hive

The term hive is applied to eusocial species with large colonies that nest inside a structure, as honey bees and stingless bees do. Stingless bee hives are by far the most diverse and their entrances are often elaborated into beautiful flower-like openings while others are simple tubes that are sometimes translucent, looking like a plastic straw. Brood cells of stingless bees are either formed in seemingly disorganized clusters or in a more regularly arranged comb. Unlike honey bees, stingless bee combs are usually horizontal and often arranged in a spiral and they are usually separated from the food storage pots by layers of wax and / or resin and the whole nest is surrounded by tougher outer layers.

A great advance in beekeeping arose with the development of the Langstroth hive, invented by Reverend Lorenzo Lorraine Langstroth (1810–1895) and patented in 1852. His design made use of his discovery that bees would not build comb or fill a space with propolis or wax if it was between approximately 6 and 9 millimeters in width. Consequently, by hanging movable combs vertically, separated by such a space, and with a lid allowing access to the hive from above, the new design was a great improvement on earlier ones. The same technology is used for the eastern domesticated honey bee, Apis ceraina, as well as the more common western one.

See also Apis; Clan Apis; Eusocial; Meliponini.

Holotype

When someone calls an organism by it scientific name—its genus and species—how do they know they have identified it correctly? Ultimately, all identifications harken back to a single specimen, the one upon which the original species description was based. This specimen is called the holotype. While the regulations as to how to describe a species in a valid manner have changed over time (for example, purely electronic publication of names has only been permitted since 2012), currently, the actual individual described is the holotype and all others mentioned along with the original description are termed paratypes.

This causes some practical problems, which include issues associated with the often substantial variation within a species. No single taxonomist will have access to all the necessary holotypes for a particular group of bees. So many will use identification keys written by people who hopefully did study the relevant holotypes. Sometimes researchers will have a synoptic collection of specimens identified by an expert who may or may not have seen the relevant holotypes. This protocol suggests that holotypes receive a lot of study and as they are usually old and often fragile, they frequently become damaged: some have the head glued to the body backward, some are completely missing the head, some are missing all the body parts that could conceivably fall off. Thus, the most important specimen that represents the species, the holotype, is often a wreck. There are regulations that enable designation of replacements for such damaged specimens, or those that have been lost—for example, if the museum holding them is destroyed by fire or warfare.

See also New Species.

Honey

Honey is concentrated nectar that bees store as food. Very few of the more than 20,900 described bee species make honey. The dozen or so species of honey bees (genus Apis) and the other perennially social group of corbiculate bees—the stingless honey bees with over five hundred species—make quite a lot of honey, while bumble bees might, at best, have a few tablespoons of it at a time. Most honey that people add to their tea, breakfast cereal, or desserts comes from just one species—the domesticated western honey bee. Its honey is stored in combs that beekeepers provide and from which the honey is easily extracted, although wild honey bee honey can be harvested through honey-hunting, which destroys the nest. Stingless and bumble bees store honey in little pots that often resemble a bunch of grapes. Extracting honey from their nests is more destructive in that the pots themselves have to be cut open. Stingless bee honey is generally more runny, acidic, and has a more complex flavor than Apis honey.

Honey color, consistency, and flavor all depend on the resources that are available for the bees to forage from—which are usually flowers, but also include extrafloral nectaries and honeydew produced by insects such as aphids. By collecting honey at a time when the hive is surrounded only by flowers of a particular type, beekeepers can get honey with the specific flavors of the nectar of that plant. Manuka honey from bees that have collected nectar only from the manuka tree in New Zealand is particularly prized, although more honey is sold under the name “manuka honey” than the bees visiting all the world’s manuka trees could possibly produce. Buckwheat honey has a particularly strong flavor.

In addition to its nutritional and gastronomic features, honey has medicinal uses, perhaps most commonly as a cough suppressant. However, honey should never be given to babies as it can cause infant botulism.

See also Apis; Bumble Bees; Hive; Mead; Nectar; Stingless Bee.

Honey Bee Declines

Previously referred to as Colony Collapse Disorder, the phenomenon is now known to be more complex with different symptoms in different parts of the world. While small proportions of colonies are usually lost during the winter, unusually heavy colony mortality rates were first observed toward the end of the twentieth century. Current understanding suggests there is no single cause, although application of a new group of pesticides—neonicotinoids—seems to have coincided with its spread. Unlike earlier pesticides that are used when a pest outbreak has happened or is predicted to happen soon, neonicotinoids are used as a prophylactic, often applied to the seeds before planting, whether a pest outbreak is expected or not. It is not surprising that there have been numerous legal battles over neonicotinoids between beekeepers and the pesticide industries. Early field studies were criticized by industry for not being performed under controlled laboratory conditions and laboratory experiments were criticized for not reflecting realistic conditions in the field. But the relationship between these pesticides and colony losses is not simple. Research has shown that there is an interaction between fungicides and neonicotinoids in increasing colony losses. Additionally, the pesticides weaken the immune response of bees and their usage also coincided with the spread of both new diseases and mites that can transmit them.

See also Agriculture; Mites; You Can Help the Bees.

Hospicidal

Cuckoo bee larvae hatch from the egg in a brood cell that may contain a living host egg or larva, and sometimes there may be additional cuckoo bee eggs or larvae also. With the potential for so much competition for the finite resources of just one pollen ball, it is not surprising that newly emerged cuckoo bee larvae are usually armed with enormous sickle-shaped mandibles and sometimes with sharp points on the labrum. The megachilid genus Stelis is an exception in that most of the host killing seems to take place when the cuckoo larva is in its last instar. These sharp armatures are used to slice away at, or puncture, host eggs and larvae or those of other cuckoo individuals. These hospicidal—host killing—larvae move about the brood cell to remove all competition and so they often have fleshy appendages that help them traverse the entire pollen ball. These larvae must often be very busy, as up to six other cuckoo eggs have been found within the same brood cell such that the winner would have to murder seven times—the host’s offspring, as well as other cuckoo bee larvae. The morphological weapons are usually reduced in subsequent molts as they are no longer needed once all the competition has been eliminated.

If the cuckoo is one that oviposits in cells that the host has already completed and sealed, it is important for the eggs to develop rapidly such that dispatching the host egg or larvae—and those of any other cuckoo bee individuals, can be completed as soon as possible. Developing quickly gives the hospicidal larva an advantage.

See also Cuckoo Bees; Larva.

Hotels

Bee hotels are human-made aggregations of tubular cavities made for bees to nest inside. They come in all shapes and sizes and are usually made of wood, cardboard, canes, or pithy stems (or combinations thereof) that mimic naturally occurring cavities that many bees use for their nests. Some of them are beautiful works of art. The tunnels are usually of a range of sizes to attract species of different sizes. Making bee hotels has become something of a cottage industry and even some chain stores carry them with the exhortation to “help the bees.” Unfortunately, this claim is not based on much hard evidence. A detailed study showed that half of the occupied hotel tubes were inhabited by wasps and that approximately half of the bee or wasp inhabitants were introduced, exotic species. While there’s nothing wrong with solitary cavity-nesting wasps (indeed, they help control pests in the garden) most people would prefer to help native bees rather than potentially invasive exotic species. Also lacking are long-term studies that show a beneficial effect of bee hotels. Because they provide artificially dense nesting opportunities, as the bees would not usually nest in such close proximity, there is potential for natural enemy populations or diseases to build up and have a negative impact on the bees (and wasps). Long-term studies are needed to assess the advisability of encouraging people to purchase a bee hotel.

See also Aggregation; You Can Help the Bees.

Integumental Coloration

Both the underlying integument and the overlying hairs of bees can have various colors. The underlying integument is dark brown to black in most bees, though dull metallic colors throughout or orange or red—particularly on the metasoma—are common. Yellow markings are also common, especially on the face of males and / or as bands on the metasoma, and less commonly as markings on the mesosoma. Some bees have very complicated arrangements of yellow markings against a dark background, as in the appropriately named small carpenter bee Ceratina hieroglyphica. A few bees are entirely pale colored, pale yellow, tan, or orange—or, very rarely, pale green. Pale colors are disproportionately found in either very small bees, such as fairy bees, or in nocturnal ones. These colors are caused by pigments in the integument, although in bees with a transparent, or semi-transparent integument, the colors may come from the internal organs.

Metallic coloration is an entirely different matter and arises in two ways. Most metallic bees get their colors from structural effects caused by nanostructures of the body surface. Most metallic bees are green or bluish, but some are orange, red, or purple, and a few have the entire rainbow. Orchid bees and many Halictinae such as Agapostemon are the best-known, brilliantly metallic, colored bees. The other way of obtaining metallic coloration arises from an effect like a sheen of oil on water. These metallic colors are relatively faint.

See also Agapostemon; Mimicry; Nocturnal and Crepuscular Bees; Orchid Bees.

Introduced Species

An introduced species is one that has been taken to outside its native range, accidentally or on purpose, by humans. Relatively few bees have been introduced on purpose, perhaps only 25 percent of the approximately eighty species known to have been translocated outside where they naturally occur. Most were transported to aid in pollination; these include the alfalfa leafcutting bee, moved from Europe to North America for alfalfa pollination, and various orchard bees (Osmia: Megachilidae) that have been taken from the eastern hemisphere to North America for pollination of fruit tree crops.

Bees accidentally transported to new parts of the globe most often arrived inside wooden structures and so, although the majority of bees nest in the ground, only approximately a dozen species out of the eighty introduced bees do so. It has been suggested that one such soil-nester was transported from Europe to the East Coast of North America in ballast used to weigh down ships with dirt while their holds for the return journey would have brought fish to Europe for Friday dinner.

An introduced species becomes an invasive species when it has a negative ecological impact within the new range. Megachile sculpturalis, the Asian giant resin bee (Megachilidae), brought to North America from Asia, takes over the nesting tunnels of native large carpenter bees, sometimes gumming up the homeowner bee with resin. One way in which invasive bees can have a negative impact on species in the introduced region is through the vectoring of pathogens to which the local native bees have no experience and little immunity. The decline of the South American Bombus dahlbomii is thought to have been caused through disease transmission from introduced European bumble bees.

See also Biogeography; Endemic.

Killer Bees

The thought of deadly swarms of stinging insects ravaging communities has been a trope of horror films for years but was given a boost by the origin of “killer bees,” since renamed “Africanized bees” as it was decided that the moniker was bad public relations, though the new name has its own awkward connotations. They arose in 1957 as a result of an experiment gone awry. A Brazilian scientist, W. E. Kerr (1922–2018), wished to improve the honey harvest of Brazilian honey bees. The local strains were docile but did not produce much honey. Kerr wanted to crossbreed them with African bees from regions in Africa that had a similar tropical climate to Brazil. These East African lowland bees (Apis mellifera scutellata) were very productive but also aggressive. Kerr hoped to produce docile productive strains and so imported some African honey bee colonies. But before he could complete his experiments, some African colonies swarmed and escaped. They hybridized with local honey bees and spread rapidly through much of South America and up through Central America and Mexico, arriving permanently in the southernmost United States in 1990. Beekeepers have learned to live with them: colony management now takes more time and is often done at night.

What makes “killer bees” particularly aggressive is their low threshold for mass attack—a slight disturbance can result in what would be an overreaction for other strains of domesticated honey bee. Scientists developed a measure for aggressivity in the bees: they counted the number of stings in a small flag waved by a mechanical toy placed outside the nest entrance after the bees had been aroused by the impact of a slingshot hitting their hive. A typical European honey bee colony stung the flag once or twice per minute, while a killer bee colony averaged a hundred stings per minute. Nowadays researchers use genetic methods to detect Africanized bees.

See also Agriculture; Apis; Sting.

Kin Selection

The social organization of bees and other insects has impressed biologists not only because of their behavioral complexity and apparent orderliness, but also because the evolution of worker sterility seems somewhat mystifying from a simple Darwinian perspective where individuals are meant to maximize their reproductive success: how can sterility evolve? One of the potential explanations derives from the insight that individuals can increase the proportion of their genes in succeeding generations not only by reproducing directly, but also by aiding the reproductive success of close relatives. This idea was elaborated in detail by William Hamilton (1936–2000) although it was John Maynard Smith (1920–2004) who came up with the term “kin selection.”

Kin selection seems to be a particularly good explanation for why so many independent origins of worker sterility (or at least reduced direct reproductive output) arose among the Hymenoptera, including the bees: haplodiploidy produces unusual relatedness asymmetries. Simply put, and assuming her mother had only one mate, a female bee shares more of her genes with a sister than she does with her own offspring. This is because all her sisters share an identical paternal genome from their haploid father. Thus, a female bee should stay at home and help her mother raise more sisters. What complicates matters is that the same female bee is less related to her brothers than she would be to her own sons: the paternal component of her genome is entirely absent in brothers. Kin selection could still help explain worker bee sterility if the workers can either bias the sex ratio to favor reproductive females or produce some male offspring themselves. This may help explain the competition over male production that occurs in bumble bee colonies.

Alternative explanations have also been invoked to explain worker sterility, one of which posits that the mother forces daughters to work for them, perhaps aided by providing them less (or lower quality) food, thereby making the smaller daughters easier to manipulate.

See also Eusocial; Haplodiploidy.

Knees

“The bee’s knees” is a common saying meaning that something is excellent. Etymologists (not to be confused with entomologists) have suggested that it might have had a somewhat opposite meaning in earlier centuries, meaning that something was of little importance—bees knees being rather small. But, in fact, there is a structure on most bees that is somewhat knee-like, called the basitibial plate—and it is important. Basitibial plates usually take the form of a V- or U-shaped raised area at the base of the hind tibia. It is more commonly found in females but whether it is present in males or females, and details of its structure, are often important in identification of particular bees. It can be in the form of an entire V or U, a partial letter with one side and / or the apex missing; its size, or whether it is covered in hair, or its edges are raised, are all features that help identify particular bee groups. In some bees, such as large carpenter bees and the Euryglossinae, it is displaced toward the apex of the tibia—more like a modification of the bee’s shin. The fact that the basitibial plate is more commonly found in females, and especially those that nest in the ground, suggests that these “knees” might be used in aiding with purchase against the walls of the burrows, thereby aiding the bee’s locomotion up and down within its nest.

See also Body Plan; Legs.

Larva

Bee larvae are the equivalent of the caterpillar stage in the life cycle of a butterfly: their sole function is to feed and grow so they can pupate and metamorphose into an adult. Unlike butterfly caterpillars, bee larvae are usually very simple in appearance and uniformly whitish-cream in coloration—nowhere near as interesting, pretty, or variable as caterpillars. Like other insects, juvenile bees have to molt in order to grow and they have five larval instars: they hatch from the egg, change their “skin” four times, and then once more to become pupae.

Other than the enormous mandibles of the hospicidal larvae of cuckoo bees, or the fleshy expansions of the body in the same instances, or where the larva has a liquid food to deal with, bee larvae have relatively few unusual morphological modifications: without the aid of a powerful microscope to study their heads and spiracles, they pretty much almost all look the same. The main exceptions are the reed bees of the tribe Allodapini—relatives of the carpenter bees (Apidae). These bees are unusual in that the juvenile stages are gathered together in a crèche at the end of a burrow, usually in a pithy stem. Thus, unlike other bee larvae sequestered inside a brood cell, they can move around. As a result, they have fleshy protuberances and complex patterns of hair that help them move around and sense their environment as they do so. Some are even somewhat shaggy-mopped, the bee larva version of the Beatles.

See also Hospicidal; Pupae.

Legs

Bee legs, like those of other insects, comprise five segments. From base to apex these are the coxa, trochanter, femur, tibia, and tarsus. The tarsus is subdivided into five tarsomeres, of which the basal one—the basitarsus—is the largest. Most female bees transport pollen on their hind legs, usually on the femur, tibia, or both. The tibiae bear spurs toward their apex. The foretibial spur forms part of the antenna cleaner; the antenna is passed between the spur and a concavity at the base of the basitarsus of the foreleg. The mesotibial spur is usually simple in structure but is toothed in some lineages such as some panurgines and cleptoparasitic Apidae. The metatibial spurs are paired and the details of their structure are important for the identification of many groups of bees. The posterior spur in particular may bear fine, parallel teeth or weak undulations; it might be serrated or developed into a comb-like structure with few to many long teeth. In many oil-collecting bees, it is developed into a press to squeeze out the oil. The metatibia may or may not possess a basitibial plate.

The apical tarsal segment is, confusingly, called the pretarsus and it bears a pair of claws and often a somewhat membranous flap between them called an arolium. Whether the claws are toothed, forked or simple and whether the arolium is present or not are characteristics of importance in bee identification.

The legs are the site of many extreme sexually selected modifications in male bees. These include swellings, spines, semaphore-signal-like discs or brushes of hair. These are used to hold the female in specific ways, brush her head, or stroke her antennae—all of which may be essential components of bee courtship.

See also Corbicula; Knees; Mating; Oil Bees; Pollen Acquisition; Scopal Hairs.

Longevity

How long does a bee live for? The answer differs depending on whether the entire life cycle of an individual or only the adult period is considered. For solitary bees with just one period of flight a year, the answer for the entire life cycle is simple—approximately twelve months. In bees with multiple generations each year, each individual is alive for substantially less than twelve months. In contrast, some solitary bees remain as fully grown larvae for approximately an extra twelve, twenty-four, or even thirty-six months: the offspring of a single female within the same nest becoming adult over several different years. In all these solitary bees, the period spent flying around as an adult is usually measured in weeks rather than months.

Among social bees, workers might die only six weeks or so after their egg was laid, while queens might live not much longer than a year if they have an annual colony cycle, but for multiple years if the colonies are perennial—perhaps three years for honey bee queens. Perhaps the longest-lived bee as an adult is in the perennial colonies of a strange little halictid bee called Lasioglossum marginatum, where the queens may live five or six years—twice the longevity of an average honey bee queen. But the true Methuselahs of the bee world are likely solitary bees from the Atacama Desert of Chile where some survive for many years, usually as fully grown larvae, waiting for rains to come, at which point they metamorphose to emerge, mate, forage, and reproduce in time with the desert bloom.

See also Phenology; Xeric Environments.

Man vs. Bee

Man vs. Bee is a humorous television series starring, and partly written by, Rowan Atkinson, who is perhaps better known as the silent character Mr. Bean. It deploys a similar comedic style to the earlier show but with spoken words. There are nine short episodes in the first season, which appeared in the summer of 2022, and a second season is being released in 2024.

The general plot follows Trevor (Rowan Atkinson) as a down-on-his-luck fellow who is offered a job to “house-sit” an enormous mansion containing numerous works-of-art, multi-million-dollar cars, and other trappings of wealth. The series begins with him being found guilty of wrecking the couple’s home and belongings. Some, but not all, of the damage has been caused directly through his interactions with a large bee that followed him into the mansion when he first arrived.

The bee varies from being a solid model to a computer-generated digital insect. While it is quite realistic, it doesn’t exactly match any British bumble bee species. Certainly, it doesn’t always behave as bumble bees would: in one vignette, Trevor traps the bee inside a microwave by attracting it to peanut butter on a slice of bread, which is not something that bees would be interested in feeding on.

One of the objectives of the program is to increase public understanding of the declines in pollinators.

See also Bumble Bees.

Mating

Mating in bees is usually accomplished in a very short time. Sometimes it is almost instantaneous, with the pair seeming to have only glancing contact before separating. Usually, it is a more protracted process with complex movements taking place both before and during copulation. Given the large number of modifications of male morphologies that seem sexually selected, a lot of physical communication must take place during courtship and mating. This can sometimes be observed—for instance, males caressing the female’s head with their antenna or stroking them with brushes or bristles on their legs or metasoma. Vibrational communication during mating also occurs, with males of some species making buzzing or piping sounds.

Some bees fly around in copula, the couple maintaining contact in the mating position while the female forages from flowers. This is most commonly found among the Panurginae but is also recorded in some other bees, such as the colletid genus Lonchopria. Sexual selection in these instances can act strongly on the surfaces that maintain contact for the extended period: in Lonchopria, these are the male’s mandibles and the female’s waist.

Mating in some Apis species is unique: the males literally explode in an attempt to inseminate a virgin queen and to plug her reproductive opening to preclude her mating with other males. However, the workers take out the plug when she returns to her natal hive allowing her the freedom of going on more mating flights with chastity belt removed. The average honey bee queen may store sperm from over a dozen different males, each of which died in their attempt to become fathers.

See also Spermatheca; Terminalia.

Mead

Mead is fermented diluted honey, often with the addition of fruits or herbs. Mead has been called “honey wine,” though the addition of honey to wine to make true honey wine is a different process compared to fermenting the sugars in honey itself. The distinction between the two has been written about at least since the time of Pliny the Elder (approximately 23–79 CE). Since diluted honey will ferment naturally, it is likely that our ancestors used honey-based alcohols before being able to make alcoholic beverages at will.

The origins of mead are somewhat obscured by time, though they are mentioned in the Rigveda, Beowulf, and Mayan codices, and more recently by Plato and Chaucer. The earliest archaeological record of mead is from around 7000 BCE in China; it has been suggested that the pottery of the Beaker culture from the bronze age served to store it, based upon chemical analyses of residues.

As mead varies in alcohol content from as weak as a lower-alcohol beer to stronger than the average wine and with a range of flavorings, the name applies to a very diverse range of drinks. Some may be drunk early in the fermentation process and are effervescent like champagne.

Mead has a long history of being drunk by warriors in way of celebration. Mead halls were social gathering places, predating and being replaced by banquet halls. While some of the earliest indications of mead production in Europe are from Spain, the use of grapes to make alcoholic drinks supplanted mead in warmer areas where grape cultivation was possible.

See also Honey; Nectar.

Megachilidae

This is a large and economically important family with the broadest array of nest site choices among the bee families. Relatively few species nest in the ground (although this is the ancestral condition for the family), others nest in pithy stems, abandoned beetle burrows in wood, snail shells, keyholes—basically any somewhat tubular cavity large enough to let them in. Some others make a nest out of resin on the surface of a stone, the fork of a branch, or attached to grass stems in a tussock. Still others build brood cells inside a clump of soft material such as horse dung or a large ball of plant or animal hairs and feathers that the bees collect themselves. Brood cells may be unlined, lined with leaves, petals, resin, plant hairs, or a more recent choice—pieces of plastic bag—or mixtures of two or more of these. While the genus Megachile is often referred to as the leafcutting bees, the genus also includes species that collect resins to line their brood cells rather than pieces of leaves or petals. This one genus also has almost the entire range of nest sites noted for bees as a whole.

Some Megachilidae are of considerable economic importance. The alfalfa leafcutting bee, unsurprisingly, is very good at pollinating alfalfa and has been exported around the world for that purpose. Orchard bees are good for pollination of fruit and some nut trees and several species have been cultivated to improve agricultural yields and for this purpose have been introduced to parts of the world to which they are not native. They are actively being managed for almond pollination in California.

See also Agriculture; Classification.

Meliponini

These are corbiculate bees commonly known as stingless bees. There are over six hundred species in forty-five genera restricted to the tropics. While they have indeed lost the ability to sting, they can inflict pain through biting soft tissues like lips, nasal membranes, and eyelids and when many of them bite, even at your relatively less sensitive scalp, they are an effective deterrent. One genus, Oxytrigona—the “fire bees”—produces a complex secretion, which includes formic acid that burns the skin.

These bees can be differentiated from all others by their weak wing veins, which are tubular only toward the base, delimiting relatively few to no cells. Such venation reduction is commonly associated with minute insects and it does seem probable that the ancestral stingless bee was indeed tiny.

While they are closely related to honey bees and both have perennial societies, the details of their social lives differ considerably. For example, when a colony divides, it is the new rather than the old queen that moves to the new nest in stingless bees. They are mass provisioning bees rather than progressive provisioners, as in Apis. Foragers are led to a good food source through pheromone trails rather than transmitting information through a dance. They also use chemical trails to gradually guide nestmates to a new nest site. As laying of pheromone trails is impossible over some barriers, such as rivers, stingless bee populations seem more likely to become isolated, thereby leading to more rapid diversification in comparison to honey bees that fly in a swarm and can cover larger distances.

Many species of stingless bee are kept for their delicious honey, a practice that has been in use for thousands of years.

See also Honey; Propolis; Sting; Tear-Drinking Bees; Vulture Bees; Wing Veins.

Melittidae

This is the second smallest family of bees. They are found throughout the northern hemisphere and Africa, where they attain their greatest morphological diversity and where they originated. There are three subfamilies. The Dasypodainae includes, among others, the pantaloon bees, so called because of the very long scopal hairs on the hind legs. The Meganomiinae mostly contains rather large wasp- and hornet-like bees. The Melittinae contains the original Melitta (Greek for bee) as well as the daddy longlegs bees. The latter is an inappropriate name as it is the females that have enormously elongate front legs in some species, used to obtain floral oils from the deep spurs of specialized oil-secreting flowers. Another melittine genus is Macropis, which collects oils from flowers where this resource is more easily obtained, not needing such unusual, gangly modifications.

All melittids nest in the ground and are on the oligolectic end of the specialist-generalist continuum. Many species seem rare, at least until good patches of their floral hosts are found—then they may be found in relative abundance. No melittid species is known to be communal or to have any form of reproductive division of labor.

See also Classification; Oil Bees; Oligolectic.

Michener

Nobody will ever have such a large proportion of humanity’s entire knowledge about bees in their memory as did Charles Duncan Michener (1918–2015). While he is best known for his work in bee taxonomy and classification, he also published on bee ecology, behavior, biogeography, morphology, life cycles, and evolution. His work on sociobiology was particularly influential. While others may have as prodigious an understanding of bee taxonomy, they are unlikely to be able to match his additional breadth of knowledge in these other areas of melittology.

Mich (as he liked to be called) published his first paper as a teenager and was still publishing at the end of his life, across a career that lasted eight decades. He also spent a few years studying Lepidoptera and medically important insects, working out the life cycle of chiggers, for example.

Mich’s PhD thesis, published in 1944, was the most up-to-date global classification and detailed morphological study of the diversity of bees at the time. Between 1944 and 2000 he published numerous detailed taxonomic studies of various groups of bees, describing many new species and genera. Then, in 2000, he updated his treatment of all bee genera, providing keys for their identification down to subgenus level. In 2007 he updated this global treatment once more, providing the world with a “bee bible” of over 950 pages.

See also Cockerell; Urban.

Mimicry

Upon being stung by a large, yellow-and-black banded, loudly buzzing bee, most potential predators (and humans) will avoid anything that looks similar. Some entirely harmless organisms have taken advantage of the fact that predators learn to avoid such patterns and sounds and have themselves evolved to look like a stinging bee. These are Batesian mimics—they look like something that will fight back without the capacity to do so. Male bees cannot sting but are protected from predators by looking (and sounding) like their mothers and sisters. Some flies, beetles, and other organisms have evolved to look like bumble bees for the same reason.

Two or more co-occurring species each with the capacity to sting might converge in appearance because predators only need attempt to consume one individual among all the similar-appearing species before the experience of being stung makes them risk averse to anything with that color pattern. This is called Mullerian mimicry: multiple bee species may converge on a similar color pattern for this reason. With multiple stinging insects appearing similar, there will also be entirely harmless insects that have evolved to look like them. Such an amalgamation of Mullerian and Batesian mimics is called a mimicry complex.

Convergence in color pattern is thought to occur as a two-stage process. In the first, perhaps a single mutation gives a vague similarity to the organism mimicked. The similarity is then improved upon by natural selection because the more similar the appearance, the less likely an individual is to be attacked by a predator.

In addition to having similar color patterns, mimics often behave in similar ways. For example, the orange Dianthidium macrurum (the long-tailed giant-pebble bee; Megachilidae) mimics social wasps that have a painful sting and that co-occur in Mexico and Central America. Their males fly around with their legs dangling down, an unusual posture for bees, but the one favored by the wasps that the bees resemble.

See also Integumental Coloration; Warning Color- ation.

Mining Bees

As the name implies, mining bees nest in the ground. The common name “solitary mining bee” really applies to the genus Andrena, but the description is an apt one for perhaps most bee species—as most are solitary and most nest in the ground. Other common names are used for some other bees that “mine”—such as digger bees and turret bees.

Different species of mining bee prefer different soils as substrates, with some preferring sandy soils and others more clayey ones. The angle of the preferred slope of the soil surface also varies, with perhaps most preferring a largely horizontal surface or gentle incline, while others choose steeper slopes including vertical cliffs. The degree of vegetation also matters, with many nesting in bare ground and others in dense vegetation, although, as nests in the former are easier to find, it is likely that the proportion of species that nest among dense vegetation is underestimated. Some Andrena species, such as the tawny mining bee Andrena fulva, prefer lawns (which are generally a wasteland for bees otherwise), becoming pests in some cases. Some bees nest in the open sun, while others prefer the shade, especially in hot climates. Some mining bees in hot dry habitats are particularly attracted to the damp provided by the entrances to caves or shade of trees or dense shrubbery.

Some mining bees build up dense aggregations so large that the surface of the soil looks completely different due to the amount of earth thrown up at the entrances as the females dig downward.

See also Aggregation; Andrenidae.

Mites

Mites, along with scorpions and spiders, among others, are arthropods of the class Arachnida. There are two major groups of mites, both of which include members that are associated with bees. However, it is now thought that mites might not form a monophyletic group and that their two major lineages, the Parasitiformes and Acariformes, arose separately within the Arachnida.

The most infamous bee mite is Varroa, a member of the Parasitiformes. It is a pest, spreading disease among colonies of western domesticated honey bees and weakening members of the hive by sucking their blood. These are relatively large ectoparasites that can most easily be seen as brown discs that stand out against the white background of larvae or young bee pupae. The other main mite enemy of honey bees belongs to the Acariformes: tracheal mites that are tiny and live inside the trachea—the internal air duct system—of the bees. They also suck on bee blood but through the walls of the tracheae, like mosquitoes living and breeding inside your lungs.

Many mites are beneficial to bees: eating microbes and helping to clean the brood cells, pollen balls, and bodies of developing bees. They are so beneficial that many bees have evolved specific structures, called acarinaria, to transport them from their natal nest to their new one. Acarinaria are usually patches of hairs for the mites to hold onto or specific areas that the mites glue themselves to. The most extreme acarinaria are found in some species of large carpenter bee in which almost the entire first segment of the metasoma forms an enormous chamber to house the mites, which get in and out through a small hole in the anterior sloping surface of the first tergum.

See also Carpenter Bees; Hairs; Monophyletic.

Monophyletic

All named groups within the Linnaean hierarchy, whether subgenera, superfamilies, or phyla, are meant to be monophyletic—which means the group contains the common ancestor and all of the descendants that developed from it. Of course, we cannot study common ancestors directly, but their features can be inferred from the characteristics that are shared by the descendants. For example, Colletidae have a concave apex to the glossa (except for a few males), its subfamily Xeromelissinae have a scopa that is (with one exception) more strongly developed on the metasomal venter than on the hind leg, and the genus Xeromelissa has the maxillary palpomeres differentiated so there are multiple different shapes among them within a single palp. These characteristics would have been present in the common ancestor of Colletidae, Xeromelissinae, and Xeromelissa, respectively. The features mentioned are not exhaustive; others will help define each of the named groups.

Monophyletic groups are contrasted to paraphyletic and polyphyletic groups. Paraphyletic groups are those in which the common ancestor would be present, but some of the descendants are not. Thus, apoid wasps would be a paraphyletic group as the bees arose from within them; short-tongued bees are paraphyletic because the long-tongued bees arose from within them. Polyphyletic groups do not contain the common ancestor and so they arose more than once.

Differentiating these kinds of groups requires the construction of evolutionary trees. Traditionally these were based upon morphological characteristics such as the examples noted above for Xeromelissa and the Colletidae. However, partly because convergent evolution and reversals are so common in such features, monophyletic groups are increasingly being based on phylogenies obtained from DNA sequences with the results often differing from those based on morphology. These new classifications often make it more difficult to construct morphology-based identification keys.

See also Biogeography; Classification; Wasps as Relatives of Bees.

Mouthparts

Bee mouthparts are extremely complex but an understanding of their structure is necessary to understand bee classification. From front to back, the first part is the labrum: a hard upper lip-like flap that may be a short simple oval or elaborated with processes, spines, or bristles, or expanded into a long trowel-like structure to carry resin as in some Megachilidae. The mandible is the insect “jaw,” usually with one or two teeth, but sometimes developed into more than a dozen sharp teeth as in some carder bees (Megachilidae). It is more robust in species that excavate nests in wood. The glossa is the actual tongue-like structure in the middle. In most long-tongued bees it bears a strengthening glossal rod. The bee maxilla is composed of numerous parts, each of which is modified differently in different groups of bees. Its basal stipes may bear a concavity filled with strong bristles, and the apical galea sometimes has a protuberance on the medial surface also with strong bristles. Arising at the junction of these two, the maxillary palps are usually subdivided into six sections, though the number can vary from zero to nine. In a few bees it displaces nectar up from deep nectaries to be lapped up by the glossa. Finally, the labium is also complex. Its most important parts (to melittologists) are the palps, of which there are usually four, although the number ranges from zero to nine. Technically, a long-tongued bee has the basal two labial palpomeres very long and the apical two short and at right angles to the basal two. The first two palpomeres seem to form a sheath around the glossa. In short-tongued bees the four palpomeres are usually similar to each other, small, and cylindrical.

See also Classification; Monophyletic; Nectar.

Napoleon Bonaparte

Honey bees are emblematic not only of things sweet but also of industriousness and social cohesion combined with strong defenses. Unsurprisingly, their representation has been co-opted for symbolic purposes by the politically motivated. Napoleon Bonaparte (1769–1821) chose the bee as his emblem, rather than the fleur-de-lis, Gallic cockerel, or lion, which were popular alternatives at the time. The reason was partly because of the history of bee symbolism in Gaul: perhaps the earliest of which was in the time of King Childeric (ca. 437–ca. 471). Childeric, the second Frankish king of the Merovingian dynasty, had been buried with several hundred gold and garnet bees. It has also been suggested that these represented cicadas—although why anyone would want these noisy insects in their heraldry is unclear. Nonetheless, most were melted down after being stolen in 1831. Given the recent execution of Louis XVI when Napoleon became emperor, it is somewhat ironic that he chose a royal organism as an emblem. Bees in gold thread decorated his coronation robes as well as the wedding dresses of both of his wives, and they are also depicted on his furniture and glassware. Napoleon also designed the flag for the island of Elba where he was banished in 1814: it has three bees in gold thread on a diagonal red band against a white background.

See also Queen; Religion; Stelluti; Utah.

Natural Enemies

Some groups of organisms that have large numbers of species that attack bees are dealt with in other entries in this book, but there are some groups in which attacking bees is a relatively rare phenomenon. The wax moth is one of few Lepidoptera species that are deleterious to bees, their larvae chewing their way through the comb produced by honey bees, thereby damaging the honey storage and brood rearing cells.

Another insect order that contains a few species that routinely attack bees are the true bugs—Hemiptera—in which some species wait at the nest entrance of a stingless bee colony and apprehend a leaving or returning forager from which it will suck the juices.

Nematodes have complex life cycles that, in some species, include living as parasites within the bodies of bees. Some of them seem to be sexually transmitted, associated with the genital capsule of males.

Woodpeckers will attack the brood of wood-nesting bees and a wider range of insectivorous birds will break into the narrower, softer, pithy stems within which some bees nest. Bee eaters catch insects, including bees, that are in flight.

Among the birds commonly referred to as honeyguides are some species that attack the nests of honey bees and feed on the wax and the wax moths within the hive. A couple of species give these birds both the common name and the broader family name of Indicatoridae because they guide human honey hunters to a hive, feeding on the remains after the honey has been harvested.

Honey badgers are African members of the weasel family Mustelidae. They have a broad diet that includes the contents of beehives, adult bees, brood, and stored food. They are remarkably unaffected by the bees’ stings.

See also Cuckoo Bees; Stylopids.

Nectar

Nectar is a sugary solution provided by plants to attract other organisms. For bees, the most important nectar is produced by flowers, but there are extrafloral nectaries on other parts of some plants that seek to attract mutualists—such as ants, which can protect the plant against herbivores; bees sometimes collect nectar from extrafloral nectaries. Floral nectar serves to attract pollinators and is the main floral reward for most insect visitors, although bees visit flowers also for pollen.

Nectar is produced in glandular plant tissues in structures called nectaries. The location of these within the plant varies; sometimes they are at the end of long floral spurs or at the end of a deep floral corolla. Desert flowers often have relatively well-hidden nectaries for the obvious reason that the nectar would dry up in the desert air if it were maintained in shallow structures. There are limitations in the depth of corolla or nectary that bees of different sizes and tongue-length can use.

Although sugars are the main component of nectar, many other chemicals may be involved including amino acids and fragrancies that, along with the color of the flower, serve to attract visitors. Some nectars contain poisonous substances that can be lethal to bees. Rhododendrons are an example, and large numbers of bees have died in parts of the world where exotic rhododendron species have been introduced for which the local bees have not evolved detoxification mechanisms.

Some flowers have colored lines or areas of raised papillae or hairs that radiate out from the center to guide pollinators to where the action is. These are called nectar guides.

See also Honey; Mead; Mouthparts; Nectar Robbing; Vision.

Nectar Robbing

Many plants have long, tubular flowers that make it difficult for many bees to reach the nectar. Some bees have developed a method of getting over this difficulty by biting a hole or slit near the base of the flowers and “stealing” the nectar. The prejudicial term “nectar robbing” is applied in such cases as the robber does not contact the anthers or stigma of the flower and so there is no chance of pollination resulting from their visits. However, it is not always the case that nectar robbing is detrimental to the flowers. With much of its nectar already stolen, a robbed flower will get many quick visitors of a more traditional sort, rather than one or a few longer ones. Or searching for nectar among flowers where many have had their nectar stolen, the robbing bees may fly and deliver pollen farther from the parent plant. Thus, counterintuitively, robbed flowers may be pollinated more effectively than those that have not been subject to the activities of larcenous bees.

Bumble bees and large carpenter bees are the best-known nectar robbers. Some bees can make use of the hole previously chewed by another bee so they can also rob the flower of nectar without the effort of making the hole. Reuse of a hole in a flower’s corolla that was made earlier can only be beneficial to the secondary visitors because the flowers replenish the nectar supply.

See also Bumble Bees; Carpenter Bees; Nectar; Pollination.

Nest Architecture

Most solitary bees nest in the ground and their nest architecture is often rather simple with a burrow leading to brood cells that may open directly into the side of the burrow or each at the end of a separate lateral branch. Some make their brood cells end to end at the end of a burrow while others have a more complex architecture with the brood cells clustered together and surrounded by a cavity, which may help aerate the cells in damp soil. For eusocial ground-nesting halictine bees, the number of branches or number of cells in a cluster might be quite large or there may be multiple clusters. Bees that nest in tunnels in pithy stems or abandoned beetle burrows in wood will generally place their brood cells end to end, or side by side across the diameter of the tunnel if the bee is small relative to the size of the tunnel.

Stingless bees and bumble bees can have very complex nest architecture. Usually there are cells housing the developing brood and separate ones storing nectar, and sometimes separate ones storing the pollen. The pots with different functions are usually in separate parts of the nest.

See also Agapostemon; Brood Cell; Eusocial; Hive.

Nesting Sites

Given that with relatively few exceptions, a bee female places all her offspring inside a single nest, it is essential that the location of the nest be chosen carefully. In suitable areas, large aggregations of nests can build up over time with the daughters all nesting near where they themselves developed. Bees that nest in the ground often choose sunny slopes (south-facing in the northern hemisphere, north facing in the south) because of the increased warmth the insolation provides. The soil between rocks in a rockery is often an attractive site, though the bees have to avoid overheating or desiccating if the rocks are close together or the weather unusually hot and / or dry. In contrast, southernmost populations of species that normally occur further north (in the northern hemisphere), may choose a slope that faces away from the sun, so the brood develops closer to their preferred cooler temperatures. Similarly, in particularly hot environments, bees may choose to nest in the shade provided by vegetation, boulders, or houses.

Bees nesting aboveground are also choosy as to where to build their nests. One small carpenter bee species was found to slow down its developmental rate when exposed to the high temperatures that occur in the pithy stems that were in direct sunlight, its preferred site choice.

See also Aggregation; Mining Bees; Nest Architecture.

New Species

Almost 21,000 species of bee have been described and many more await discovery. Indeed, between 2013 and 2024, over 900 new bee species names were published. How does a taxonomist discover new species? First, they must have a good understanding of the diversity of bee species in a particular group and / or geographic area so they can differentiate a new species from all previously described ones. With this knowledge, there are three main ways in which undescribed species are discovered: looking for outliers while sorting through large numbers of specimens from museums, performing genetic analyses such as DNA barcoding, and finding undescribed clusters. The third, and most enjoyable, way is to go to a relatively understudied part of the world and collect bees there (with the necessary permits). It is hard to beat the feeling of finding an organism that nobody has ever seen before (or at least for which no permanent record has been left). Putting out traps is a good way to find large numbers of specimens that may include undescribed species. It is possible, though, to discover new species almost anywhere—one new species was discovered in downtown Toronto, as it belonged to a group of bees that are very difficult to identify.

To actually describe the new species certain protocols have to be followed, the most important of which includes a diagnosis on how to tell the new species apart from others, a detailed description of the holotype, a statement on what variation there may be among other specimens (if there are any), an explanation of why the new name was chosen, and a list of where specimens were collected and where they will be housed.

See also Classification; DNA Barcoding; Mono- phyletic.

Nocturnal and Crepuscular Bees

It is easy to tell whether a species prefers to fly under low light conditions by looking at the size of their ocelli (the three facets on the top of the head). In bees that are active under low light intensities, the ocelli are relatively enormous, often with a diameter much greater than the distance between them and the compound eyes (as in the drawing of one of the best known nocturnal bees, Megalopta, shown below). The compound eyes are also usually enlarged in comparison to those of diurnal bees. Dim-light foraging bees usually also have reduced pigmentation; as is the case with cave organisms, they need not bother to produce pigments when nothing is likely to see them (and unlike moths, bees will remain hidden in a nest during the day). Pale brown is the normal body color for these bees although if their relatives are strongly metallic, they may have relatively weakened greenish reflections.

Some dim light foraging bees can orient to their nests and find flowers in light intensities that are less than a trillionth as bright as a sunny day. Yet their visual acuity is apparently only around thirty times greater than that of day flying bees. Despite this, at least some nocturnal bees can see colors. Unsurprisingly, nocturnal bees seem to be active more often on nights during and around a full moon.

Dim light flying bees need flowers that open in dim light, among which the evening primroses (Onagraceae, such as sundrops) figure prominently.

Dim light flying bees likely have reduced competition for floral resources and suffer less from enemies that enter the nest while they are foraging, although there are a few cuckoo bees that can attack in relative darkness.

See also Vision.

Oil Bees

While most bees provision nectar as an energy source for their offspring, some collect floral oils. Oil-collecting has evolved multiple times among the bees and there is a wide range of morphological adaptations for exploiting this food resource. The long-legged bees have specialized oil-mopping hairs at the end of their front tarsi. As their oil-producing hosts bear the oil-producing structures at the end of floral spurs; the forelegs of these bees are often bizarrely long.

Some oil-producing plants store the oil in structures that must be punctured. Strongly modified hairs serve this purpose with rows of robust bristles or thick spatulate hairs usually on the front leg. Some plants have the oils freely available on the surface and oil bees such as the apid Ctenoplectra mop it up with bunches of straggly hairs on the underside of the metasoma. Transporting the oils often requires specialized structures. Especially dense scopal hairs may permit this, with the oils sticking to them like paint to a paintbrush. Another approach is for the bees to have densely plumose hairs that form a sponge-like structure with some longer, stronger hairs intermixed to give some structural integrity.

Depositing the oil into the brood cell also requires special adaptations as the oils must be squeezed out from the scopa. The hind tibial spurs usually serve this function, to which end those of oil bees are large and triangular, with the area increased by robust spines. The name of the aforementioned oil bee genus Ctenoplectra is a description of these oil-squeezing, plectrum-like structures.

See also Melittidae; Scopal Hairs.

Oligolectic

Some bees will collect pollen from a wide range of flowers, others only from a few closely related ones, and some only from a single species of floral host. Generalists, such as the honey bee, are termed polylectic, specialists with few floral hosts are called oligolectic, while those with only a single host species are termed monolectic. The polylecty–monolecty continuum applies to pollen collection; most oligolectic bees will obtain nectar from a wider range of floral hosts than they will use for pollen.

Oligolectic bees cannot persist in the absence of their preferred floral hosts and are expected to persist in more restricted ranges than generalists; this might make them more susceptible to becoming endangered. This is not such a problem if they collect pollen from superabundant sources, such as willow pollen in spring or sunflower pollen in summer.

Oligolectic bee larvae often have specific adaptations for digesting the single-source pollen. Some pollen does not have all the amino acids that a bee needs for growth and larvae that receive only such pollen in their food need the biochemical machinery to produce them themselves unless they can get them from their microbiome. Some species are known to require their specific preferred pollen—if the larva is transferred to a pollen ball with pollen from a different floral source they will not survive, whereas others can do well on a wider range of pollens than the ones their mother collects for them. Polylectic bees fed on a narrower diet may not do so well, and an experimental diet of pollen that does not provide the full range of essential amino acids may cause them to starve.

See also Nectar; Pollen Acquisition.

Orchid Bees

If you take some rosemary oil out into a tropical forest in Central or South America and soak a sponge in it and leave it out hanging from a thorn on a bush, you may soon be rewarded by anywhere from several to hundreds of gaudy orchid bees attracted to the bait. While some are mostly black, most have brilliant metallic coloration with greens and blues predominating, but often with copper to red or purple reflections. It is only males you will find attracted to the chemicals that they collect. They have special brushes on their front legs to mop up the fragrance, which they transfer to their middle legs, which are specially modified to pass the chemicals onward to spongey storage tissues inside their enlarged hind tibiae. Males use the complex bouquets from the fragrances they collect to attract females. It is the males that give the bees their common name as they are particularly attracted to the fragrances produced by orchid flowers. Because orchid pollen is held in paired pollinia—lobe-shaped structures that stick to a flower’s visitor—it is common to find these stuck to the tops of the bees.

There are five genera of orchid bee; two of them are cuckoo bees. Among the nest-building species, the most diverse genus is Euglossa, which have a white labrum. One of the other genera—Eulaema—is made up of large bumble bee–like species usually with black and orange color patterns. The third is Eufriesea, which are intermediate in size usually with extensive metallic coloration beneath relatively dense hairs.

Some orchid bees have tongues longer than their bodies, as can be seen in the drawing.

See also Apidae; Cuckoo Bees; Mouthparts.

Orientation Flights

As central place foragers, female bees must return to their nest repeatedly. To permit this, they perform orientation flights. A bee that is leaving its nest for the first time will seem nervous and indecisive. After a while, they may come out of the nest and perhaps only walk around in a circle before returning. Later, they fly around in a small circle before returning again. Gradually, they appear more confident and fly in a spiral of ever-increasing diameter around the nest entrance, all the time looking toward their home. What they are doing is committing to memory the appearance of the area around their nest so that they can find it again when they return. If you find a bee nest and place some objects around it overnight, the bee will notice the change in its surroundings and learn the appearance of the new environs. If a day later you move the objects nearby while the bee is out foraging, retaining the same pattern among them, the returning bee may search the middle of the area that is surrounded by the moved objects but not where their nest is. It might take them some time to find their actual nest. If the area around their nest is disturbed by footprints or tire tracks, they may also have difficulty relocating their nest, though they are usually successful eventually even if they have to dig through some disturbed soil to get to the obscured nest entrance. Similar principles apply to bees that nest in aboveground locations, although they have to recall their nest’s location in a three-dimensional environment.

See also Central Place Foraging.

Ovaries, Ovarioles, and Oocytes

Most female bees have two ovaries each with three ovarioles, and, while they can start developing more than one oocyte (egg) simultaneously in each of them, they can usually only mature a single egg in an ovariole at a time: most solitary bees will mature just a single egg at a time among all their ovarioles. There are exceptions to both patterns. A characteristic of most Apidae is that each ovary contains four ovarioles, for a total of eight rather than six. Nomadine cuckoo bees take this increase further with up to seventeen ovarioles per ovary. Cuckoo bees are also often exceptional in having the ability to mature multiple oocytes in an ovariole. Thus, they can take advantage of successful intrusion into a nest in which there are multiple brood cells available for oviposition through both increasing the number of ovarioles and the number of mature eggs each ovariole contains.

Social bee queens often have much greater reproductive output. Queen honey bees have up to two hundred ovarioles, each capable of producing multiple eggs a day, while the workers, despite having up to a dozen ovarioles per ovary, produce no eggs at all under normal circumstances.

Although relatively unstudied, some bees can resorb the materials in an egg before it is laid. This is useful if, for example, bad weather precludes completion of a pollen ball preventing oviposition for some time, as the nutrients can be recycled.

See also Spermatheca.

Overwintering

In temperate regions the winter is a period when bees have to use as little energy as possible because they cannot replenish themselves. They enter diapause—a physiological state that requires a return of specific favorable conditions after a particular time before they come out of their “slumbers.” Species with only a few weeks of foraging activity have to spend most of the year in such programmed inactivity. If they are active only in spring, then they will often spend the winter as an adult, ready to start reproducing as soon as the weather warms enough. Species that are active in summer or fall will usually overwinter as fully grown larvae—larvae that have defecated. Once the weather warms enough (and for long enough) they will pupate and metamorphose into the adult state. Bumble bees and most species of halictine are unusual in that only mated females survive the winter, having mated the previous year. These females will have ample fat stored in their bodies and concentrated nectar stored in their crop to help them survive the winter and reactivate themselves in spring.

Most ground-nesting bees spend the winter beneath the frost line and so do not experience sub-zero (centigrade) temperatures. Aboveground nesters, such as those that nest in raspberry canes, must often survive temperatures well below freezing.

See also Phenology.

Phenology

The life cycle pattern that organisms exhibit during the year is called phenology. Some bees are active only in spring, some only in summer, and others only late in the year. The European ivy cellophane bee—Colletes hederae—is primarily active in October, unusually late in the year for any northern hemisphere species. Populations of some bees have two or more generations a year—with more generations in warmer areas if there is enough moisture to ensure flowering and food availability. Some bees have a more complex pattern, with some individuals from the same brood becoming adults the year after their natal nest was initiated and others waiting until the second or third year.

Social bees have a more complex phenology. If the colony cycle is an annual one, then mated females survive the winter and initiate nests in spring and produce a brood of workers that may forage for their mother to produce even more workers; alternatively, the colony may switch to producing males and next year’s queens straight away. In these bees, the larger queens are found in spring, the smaller workers in summer, and males mostly only later in the year. Species with perennial colonies will have a particular time of year that the colonies divide through swarming, the timing of which varies both by species and by location of the population.

See also Eusocial; Overwintering.

Pollen

Pollen grains are the parcels whereby flowering plants get the male gametes from the anther of a flower to a stigma. Pollen grains of different taxonomic groups of plants are sufficiently diverse in shape and size to allow at least an approximate identification simply from the pollen load of a bee, lake sediments, pack rat middens, or fossils. It is possible even to identify the origin of digested pollen because the outer coat—called the exine—is largely indigestible and bears the spines, ridges, and bumps as well as maintaining something of the shape of the pollen grain itself, and these markings differ among the species. The same resilient nature of pollen grains permits their identification from ancient sources dating back as far as the Cretaceous period.

Pollen is used as a food source by numerous organisms in addition to bees, ranging perhaps from thrips that pierce individual pollen grains to humans that will consume vials-full of what is awkwardly referred to as “bee pollen”—pellets of pollen removed from honey bee corbiculae as they return to the nest.

While pollen may be the main protein source for bee larvae (also providing lipids and micronutrients), adult female bees must feed on pollen to mature their eggs. The protein content of pollen varies considerably among plant species but is often higher even than in beefsteak.

See also Oligolectic; Pollen Acquisition; Pollen Ball; Pollination.

Pollen Acquisition

With very few exceptions, bees collect pollen as a food source for the next generation and they have numerous adaptations to collect it efficiently. Perhaps the easiest way bees collect pollen is found in some megachilids visiting asters; they can be seen rubbing or tapping their metasomal scopa over the tips of the anthers and the pollen goes from flower to scopa directly without any intermediary manipulation. However, most bees move the pollen from one part of their body to another. Some loosen pollen with their mandibles and pass it from their front to middle legs and thence to a scopa on the hind leg. Some flowers have the pollen deep in the corolla and bees first obtain it with special hairs on their faces and then move it to the scopa. Many bees can be seen with pollen all over their bodies, but it is eventually moved to the scopa through grooming movements, sometimes occurring while the bee is in flight.

Pollen collection is aided by the somewhat sticky nature of the coating of pollen grains. Grass pollen lacks this coating and the grains are tiny and dry. Some bees specialize in grass pollen, but they must get up very early in the morning to do so—when the air is moist, making it easier for the grains to be retained in their scopa.

See also Buzz Pollination; Hairs; Pollen Ball; Scopal Hairs.

Pollen Ball

Most bees are mass provisioners, meaning that all the food required by an offspring is provided for it in a brood cell before the egg is laid. These provisions are usually in the form of a pollen ball, a mass of pollen moistened with nectar and shaped into a round or somewhat loaf-like “ball.” In bees with sexual dimorphism in size, the pollen balls may differ in shape: those destined for the smaller sex may be spherical, while the larger ones more oblong. Most commonly, the nectar is added at the end of pollen collection and the ball is then molded into shape. Oil bees replace all, or most, of the nectar with floral oils that are mixed with the pollen.

Presumably to reduce the chances of contamination from the substrate, bees often limit the contact between the pollen ball and the brood cell by raising it on a pedestal or a few triangular “legs.” This is most important in bees that do not line their brood cells. Interestingly, Perdita—fairy bees (Andrenidae)—the largest genus of bees that do not line their brood cells, cover the pollen ball with glandular secretions that likely serve the same purpose of protecting the food from contamination. Colletids and some other bees make comparatively liquid provisions for their offspring, and these will fill the bottom of the brood cell. In these bees, there is relatively little pollen in the food mass and much of the larva’s nutrition comes from the microbes that grow in the liquid provisions. It was discovered in 2017 that much of the nutrition most bee larvae get comes from microbes growing in the pollen ball, making bees omnivorous rather than strict herbivores.

See also Brood Cell; Nectar; Pollen; Pollen Acquisition.

Pollination

Pollination occurs when the male gametophytes of a flower—the pollen—are transferred from the male reproductive parts (the anther) to the receiving surface on the female reproductive parts (the stigma). The pollen grains then germinate and a tube carries the genetic material to the oocyte deeper in the flower to achieve fertilization. Some plants have the male anthers and the female stigmas on separate flowers or even on separate plants, but the majority have male and female parts on the same flower. Pollination is affected by a wide range of agents including the wind. Animals as small as tiny midges to as large as civets can be responsible for pollinating. Bees are the most important pollinators and, except for a few wasps, are the only pollinators that carry pollen around for their own benefit—as food for the next generation. When bees visit a flower to acquire pollen or nectar, they will often leave some pollen behind, thus losing a small proportion of their collection but enabling the plant to reproduce. While most flowers will have a range of different visitors, there is variation in the effectiveness of different visitor species and it is inaccurate to assume that any floral visitor actually serves as a pollinator. A classic study of flower visitors to watermelon in California found, sadly, that the most efficient pollinator was the one that was most sensitive to deterioration of habitat quality around the fields.

See also Agriculture; Buzz Pollination.

Productivity

Most insect females lay hundreds to thousands of eggs. Bees are different: the larvae develop within a nest and have been provided with all the food they need to complete their development. The mother bee does not need to lay as many eggs because each is so well cared for. A recent compilation found that half of the bee species with available data produced less than a dozen offspring and some of the most fecund females were of agriculturally managed species with unnaturally ideal conditions for reproduction. Most bees seem capable of laying around one egg a day—of course, this includes collecting all the resources the larva that emerges needs to become fully grown. Most adult female bees last only a few weeks and will often not forage every day because of a need to construct a new brood cell, mature an oocyte, and / or due to inclement weather. This may help explain why bee lifetime fecundities are often so low.

Social bee queens usually produce more eggs, with honey bee queens producing up to perhaps 2,000 a day, and up to 750,000 in a year, though these are likely upper extremes and, of course, most eggs become workers rather than reproducers. Bumble bee queens might lay a few hundred eggs, again with relatively few becoming reproductive and most becoming workers.

See also Eusocial.

Propolis

Propolis is a mixture of wax, resin, and salivary secretion that is used in the nests of social corbiculate bees: honey and stingless bees. The plant sources for the resinous portion are very variable spatially and temporally with the result that propolis varies considerably in color and other properties, such as hardness.

Honey bees use propolis mostly as a sealant covering cracks and other small gaps within the hive. Stingless bees make more extensive use of it, as most of the structure of their nests, the brood combs, food storage containers, and so on, are constructed with it (in the case of honey bees, wax alone fulfills these tasks). Some stingless bees add soil to the resin and wax mixture to make their propolis. The elaborate nest entrances of stingless bees are often made of propolis and it can aid in nest defense because some natural enemies attempting to gain entrance to the nest may become entangled in sticky variants of it. Bees may also plug the nest entrance with a ball of propolis.

Propolis has antimicrobial properties, reducing fungal and bacterial growth within the colonies. As a result, propolis is used in traditional medicines and there has been much research into the medical benefits of propolis and the individual chemicals found within it. In addition to antimicrobial activity, some types of propolis have been found to have anticancer, antioxidant, anti-inflammatory, and immunoregulatory effects. In one case, chemicals from propolis were shown to reduce oral bone loss following gingivitis (albeit in mice).

See also Apis; Hive; Meliponini.

Proverbs

There are hundreds of interesting quotations and proverbs associated with bees. Here are just a few:

“Not a single bee has ever sent you an invoice. And that is part of the problem—because most of what comes to us from nature is free, because it is not invoiced, because it is not priced, because it is not traded in markets, we tend to ignore it.” —Pavan Sukhdev

“When the bee comes to your house, let her have beer; you may want to visit the bee’s house some day.” (African proverb)

“When you shoot an arrow of truth, dip its point in honey.” (Arabian proverb)

“The bee, from her industry in summer, eats honey all the winter.” (Unknown origin)

“He who would steal honey, must not be afraid of bees.” (Danish proverb)

“The buzzing of the flies does not turn them into bees.” (Georgian proverb)

“The king of the bees has no sting.” (Portuguese proverb)

“A bee is never as busy as it seems; it’s just that it can’t buzz any slower.” —Kin Hubbard

“Aerodynamically, the bumble bee shouldn’t be able to fly, but the bumble bee doesn’t know it so it goes on flying anyway.” —Mary Kay Ash

“Handle a book as a bee does a flower, extract its sweetness but do not damage it.” —John Muir

See also Honey; Nectar; Sting.

Provisioning

Provisioning is the word used to describe the way bees provide food for the next generation. There are two broad categories: mass and progressive provisioning. In the former, all the food needed for the development of the individual is gathered together in a brood cell, usually before the egg is laid. In progressive provisioning, food is given to the developing larva as it grows.

Mass provisioning means that the final size of the pollen ball has a major impact on the size of the offspring. As the males of most bees are smaller than the females, smaller provision masses generally result in males and larger ones in females. The sexual size dimorphism is reversed in some bees with aggressively territorial males where larger individuals are more likely to win in battles.

Little is known about how readily a female solitary bee will change the sex of the offspring if the day’s foraging is interrupted by poor weather or scarcity of resources, but experimental addition of pollen has been shown to bias the sex of the offspring toward the larger sex.

Progressive provisioning means that there are repeated interactions between the developing larva and the adult(s) that provide it with food. A disadvantage of progressive provisioning is that the length of time the juvenile is dependent upon feeding is extended. It is found in social species: honey bees, bumble bees, and most reed bees.

See also Body Size; Brood Cell; Haplodiploidy.

Pseudocopulation

Some orchids trick males into misidentifying their flowers as females of the insect’s own species. The males then attempt to mate with the flowers and if they try this for a second time, they may affect pollination. These mating attempts are termed pseudocopulation and the flowers often bear such similarity to a female that the males deposit sperm on the flowers. The term has also been used to describe the attempts of male bees to mate with groups of oil beetle triungulins, which is the beetle’s way of getting into a bee nest.

Flowers of orchids such as the bee and spider orchids (genus Ophrys) attract male bees to pollinate them by looking like, feeling like, and smelling like a female bee. While to our eyes they may not look much like a bee, the overall shape, size, and reflectivity of the lower petal—the labellum—are sufficiently similar given the bee’s relatively poor powers of visual discrimination. The sides of the labellum are relatively hairy, whereas its middle is somewhat reflective, as are bee wings. The flowers also give off chemicals similar to the sex pheromones produced by female bees. Given that species-specific sex attractants are involved, it is not surprising that there is often some specificity between the male bees and the flowers that attract them. The common European long-horned bee Eucera longicornis (Apidae) is most attracted to the bee orchid (Ophrys apifera), while other Ophrys species attract male solitary mining bees, cellophane bees, or wasps.

See also Mating; Mimicry.

Pupae

The pupa is the stage in the life cycle between larva and adult. It occurs in insects with complete metamorphosis. The fully grown post-defecating bee larva molts into the pupal stage from which the adult emerges. The bee pupa has the same overall structure as the adult but with reduced wings, and the legs and antennae are at least partially folded over the body surface. While the pupae of some bees are somewhat hairy, these are not the hairs that will be obvious in the adult bee.

The pupa starts off as white as the larva that preceded it. Gradually, the underlying adult’s coloration becomes apparent, starting with the eyes, which go from pink eventually to black. The adult integumental colors usually start appearing as the eyes darken and the hairs may attain their color before the underlying integument does. Soon before emergence, the pupal exoskeleton appears as a flimsy skin covering the adult underneath, the hairs are visible through it, and, even in some bees that lack metallic coloration, there may be a weak, oily sheen.

Within the larva, there are small groups of cells called imaginal discs. There is one for each antenna, compound eye, leg, and so on. They remain small in the larvae but start growing when pupation occurs. They grow because materials that formed most of the mass of the larva are recycled to form the tissues of the adult. The brain is one of the body parts that remains largely intact throughout metamorphosis.

See also Body Plan; Larva.

Queen

In a semisocial or eusocial society, the reproductively dominant individual is the queen. In annual colonies, these females may start a nest alone and aren’t technically “queens” until they have workers to work for them (one isn’t a queen until one has subjects). In perennial colonies, queens are never alone as new colonies form through fission or swarming. In some eusocial colonies, if the queen dies, a worker may develop her ovaries and become a replacement queen in what is now a semisocial society.

Queens are typically larger than workers and those in perennial colonies may be remarkably different in structure. Honey bee queens, unlike the workers, can sting multiple times without losing their sting apparatus because their sting shafts are not barbed and they do not have a well-developed corbicula as they do not need to transport pollen. They also have much larger ovaries with many more ovarioles than workers. Stingless bee queens may become physogastric—their metasoma so swollen as they become egg-laying machines that they become incapable of flight. Even in species with annual colonies, the queens and workers may be so morphologically different they have sometimes been described as different species. In many social halictines, the queens and workers overlap in size to varying degrees, although the queen is usually larger than her own workers. Even in cases where morphological differences between queens and workers are minimal, the two castes can be differentiated because queens have well-developed ovaries and their spermatheca contains sperm, whereas workers may or may not have been inseminated but will have less well-developed ovaries.

See also Eusocial; Ovaries, Ovarioles, and Oocytes; Semisocial.

Religion

Bees are important in some way to all religions not only through the sweetness of honey and the use of wax in candles but also through their seeming ability to live in effectively cooperative societies.

In Buddhism, one month is referred to as honey full moon (Madhu Purnima) and offerings celebrate a monkey’s gift of honeycomb to the Buddha.

Monasteries and nunneries often kept bees and prized their social cohesion and the chastity of the workers as well as their sweet products.

Hindu texts refer to both the honey and stinging side of bee biology. Vishnu and Krishna are also known as Madhava—or “nectar-born.” In contrast, Kama, a goddess of love, is sometimes depicted as armed with a bowstring of bees, somewhat like cupid.

In Judaism, honey symbolizes the sweetness of life and is consumed on many religious holidays. Honey also symbolizes the sweetness of the words of the Torah. While bees are not kosher, honey is considered acceptable because it is only stored by the bees and does not come from their bodies directly.

The Mayan god of bees and honey—Ah-Muzen-Cab or Ah Mucencab—is often depicted with the wings partially spread as if about to take off, with the head downward, giving it another name: the descending god, best known from a bas-relief on a temple in Tulum, Mexico.

“Surah-al-Nahri” is the sixteenth surah of the Koran wherein God’s actions are manifest through the perfect hexagons of the honey bee comb and honey is said to have healing properties when accompanied by a belief in God’s power. But honey is also considered risky, as without proper care it can ferment.

See also Bugonia; Utah.

Robber Bees

Stingless bees build large nests within which they store food as well as rear brood—an enormous quantity of resources that are attractive to other organisms. Some stingless bees have evolved to raid the nests of other species where they steal not only the food supplies but also nesting materials. This lifestyle has evolved twice among the stingless bees, leading to the genera Cleptotrigona and Lestrimelitta.

Robber bee scouts search for suitable nests to attack and when they have discovered one, they recruit some of their nestmates so that large numbers can invade the luckless host colony. Some potential hosts have permanent soldiers flying around outside the nest entrance, constantly on the lookout for robber bee scouts. The robber bees’ attack involves scout bees that bear some chemical similarity to the attacked hosts to avoid detection, and the release of mandibular gland pheromones that both recruit large numbers of robbers and cause at least partial paralysis among the attacked host bees.

Robbing also occurs in honey bees: a hive that has depleted resources will sometimes attempt to obtain some, especially nectar, from another colony, usually seeking out a relatively small one with weakened defenses. In this case, it is not a characteristic of populations or species, but rather a strategy employed under specific, reduced circumstances.

See also Guards; Meliponini; Vulture Bees.

Sampling Bees

Until relatively recently, the only people interested in sampling bees were taxonomists and those interested in pollination biology. With concern about biodiversity in general and bees in particular, bee sampling methods have become increasingly studied. Traditionally, bees would be sampled with an insect net: a bee is seen and swiped at. For ecological purposes this is not readily standardizable, as even the same person in different decades of their life, or in different moods on the same day, will have different bee catching abilities even in exactly the same place.

Passive trapping is more repeatable and considered more scientific. The most common method is to use pan traps: brightly colored, usually white, yellow, and blue and often fluorescent, partially fluid-filled plastic bowls or cups that are left out for some time. Vane traps, usually blue, are two plastic vanes inserted into a funnel on a bucket. As with pan traps, bees are attracted to vane trap colors. These passive methods are particularly good at sampling over large areas, especially where bee density is so low, as in extreme deserts, that using a net would mostly be fruitless.

Working on visual attraction, these methods are poor at catching nocturnal or crepuscular bees. Malaise traps—tentlike structures with open sides, a middle baffle, and a collecting bottle at the top of a sloping roof—are often effective for nocturnal (and other) bees but, as these can easily capture a liter of insects in a day, sorting through everything to find the bees is time-consuming.

Some bees are attracted to specific baits, including fish skin, though specimens obtained using this method are rather smelly. Orchid bees are particularly readily sampled using a range of chemicals of which cineole (found in eucalyptus oil) is often considered the best. Only male orchid bees are attracted to these chemical baits.

See also Databases; Orchid Bees.

Scopal Hairs

Most bees have one or more areas on their body where the hairs are specialized for carrying pollen. The hairs that perform this task are called scopal hairs. The location of scopal hairs varies among different taxonomic groups. In most bees, the scopa is best developed on the hind legs, sometimes on the femur, sometimes on the tibia, and sometimes on both. The basitarsus may also be involved. Megachilidae, except the cuckoo ones, generally have the scopa on the underside of the metasoma. Other body parts may be involved with pollen transport. For example, bees in the genus Andrena have long curved scopal hairs on the trochanter and sides of the propodeum, in addition to shorter ones on the femur and tibia. The spiral-horned bees (Systropha) collect pollen not only on the hind legs and underside of the metasoma but also on the sides of the mesosoma and the dorsal surface of the metasoma.

Scopal hairs vary in length, density, and structure. Especially in bees that moisten the collected pollen with nectar, the scopal hairs may be quite sparse and without branches. Bees that collect relatively fine and dry pollen have dense hairs with numerous branches that help hold the pollen in place.

Some bees do not have scopal hairs—male bees and cuckoo bees do not collect pollen and so do not need them. Masked bees (Hylaeinae) and the Euryglossinae of Australia do collect pollen but have no scopal hairs because they carry the pollen back to the nest within their digestive system rather than on the outside of their bodies.

See also Corbicula; Cuckoo Bees, Hairs; Pollen Acqui- sition.

Sculpture

Numerous artists have used bees as an inspiration or as collaborators in making sculptures.

Aganetha Dyck and Tomas Libertiny, for instance, have both used honey bees to help construct sculptures. One of Libertiny’s pieces recreates the head of Hadrian based on the ancient bronze statue held at the Israel Museum. He made a 3D model of Hadrian’s head out of nylon covered in wax paper and placed it in a hive. The second attempt resulted in a complete sculpture in only four days, though admittedly the artist had thousands of little helpers. In an interesting reversal, the new sculpture is made of wax, whereas the original would have used wax as part of the process resulting in a sculpture made purely of bronze.

Pierre Huyghe’s Untilled is a reclining nude sculpture made by a different artist, with honey bee comb and the associated tens of thousands of bees on its head. Visitors have to be kept at a distance from this living sculpture.

Both the British artist Wolfgang Buttress and the Canadian Sarah Peebles have constructed artworks where the activity of bees directly influences what visitors see, in real time. Peebles has also developed attractive wooden sculptures with tunnels drilled in them to attract cavity-nesting bees. Each block of tunnels has clear plexiglass on one side. These “audio bee cabinets” are fitted with microphones so that visitors can both watch and listen to the activities inside the nests.

See also Apis; Cavity-Nesting; Hive; Wax.

Semisocial

While a reproductive division of labor in bees usually occurs between queens and their worker daughters, sometimes it arises between individuals of the same generation: such societies are referred to as semisocial. These societies arise in two ways: overwintered females remain associated with the natal nest (or at least natal nestmates) and form a society the following spring with one becoming reproductively dominant over the others, or the original queen in a eusocial society dies and one of her daughters becomes a replacement queen while the remaining sisters function as workers. The former is often an intermediary stage leading to a eusocial society when the first worker brood females emerge, perhaps with a mixed phase if worker daughters co-occur with some late-surviving overwintered subordinates. In rare cases, semisociality is the peak of social organization as seems to happen in some southern South American Augochlorini in which there is never a eusocial phase later in the relatively short summer. Having semisocial societies arise through the death of the original queen is inescapable in situations where the queen may have become parasitized, eaten, or simply died of old age in an extended period of spring, summer, and perhaps fall activity. Which daughter becomes replacement queen when a family is orphaned is determined by either age, size, or a combination of the two. One reason semisocial societies may be less common than eusocial ones is that the workers, instead of working to produce full sisters, are raising nieces, to whom they are less closely genetically related than they would be to their own daughters.

See also Eusocial; Halictidae; Haplodiploidy; Queen; Worker.

Sexual Dimorphism

In addition to the standard differences of (usually) one more flagellomere and one more metasomal segment in males, the different structures of the reproductive system, and the presence of nest constructing and pollen collecting structures in females, there are additional differences between male and female bees. Females are usually larger, the metasoma often being particularly wide in comparison to that of the more cylindrical male because of the extra room required to develop eggs. Sexual size dimorphism may be reversed in species with territorial males where being big is advantageous.

Males often bear unusual sexually selected modifications. These can be of almost any body part: crenulated antennae, bristles on the legs, massively expanded hind legs, processes on the underside of the mesosoma, and combs of bristles on the metasoma, or even all combined on the body of a single individual. Some of the most elaborately modified males are in the nomiine genus Pseudapis (Halictidae), which may have long beards on the lower surface of the head, a plate-like apical tarsomere to the middle leg, ridges on the underside of the mesosoma, massively expanded hind femora, sickle-shaped hind tibiae, strangely expanded semitransparent enlarged hairs on the hind leg and underside of the body, as well as spines, brushes, combs, prongs, and hooks on the metasomal sterna. All these in addition to the strongly modified genitalia that are more generally found among male bees. It is these sexually selected structures that are most often used by melittologists to differentiate otherwise similar species.

See also Antennae; Body Plan; Mating; New Species; Sting; Terminalia.

Slim Harpo

Slim Harpo (1925–1970) was born James Isaac Moore. He was well known for his swamp blues style and for playing the “harp,” another term for the harmonica. He was known for a while as Harmonica Slim, from which Slim Harpo is only a slight emendation; the name change was necessitated because there was another blues performer known by that name.

His greatest hit, and main relevance for a book on bees, was “I’m a King Bee,” a song that has been covered by other artists, including Pink Floyd and the Rolling Stones, over the years since it was released in 1957. It was entered into the Grammy Hall of Fame in 2008.

Of course, melittologists would be a little skeptical of the lyrics of a song called “I’m a King Bee,” because there is no such thing. Unlike the case in termites, which have kings and queens, ants, bees, and wasps have queens that do not have any lasting association with any male—other than mating and then storing their sperm. Indeed, if the reference was to honey bees—and in the deep south of the United States, they would have been the only bees with royalty that would be seen frequently—the reference would have been to a drone. But neither “I’m a King Termite” nor “I’m a Drone Bee” have the same ring.

See also Queen.

Snapping

Bees that nest in pithy stems can be studied with relative ease compared to those that nest in the ground where the melittologist must dig them up. Just as with ground-nesting bees, stem-nester nests need to be obtained for study while all the occupants are home. This necessitates an early start to the day and / or a late end—though early mornings are preferred as it is cooler and disturbed bees less likely to escape.

The researcher wanders around a site with suitable nesting stems looking for a nice clear circular hole in the broken end of, for example, a raspberry cane, sumac twig, or, in Australia, a broken flowering spike of a grass tree. The large flowering stalks of agave or century plants in the western hemisphere may bear nickel-sized, perfectly circular holes that are the entrance to a large carpenter bee nest, though collecting the latter more often involves sawing than snapping a twig.

Once a potential nest has been found, the entrance is plugged (a piece of tissue paper will do), the twig or stem snapped (or sawn) a suitable distance below, and the snapped stem placed in a cooler. Once back in the laboratory the stem can be cut open and the occupants studied in as much detail as required.

It is relatively easy to find dozens of nests for study in a single day when snapping twigs, while it is usually impossible to get more than a few nests a day when digging them up.

See also Carpenter Bees; Digging; Nesting Sites.

Social Parasitism

While cuckoo bees make brief intrusions into a host nest, social parasites coexist with their hosts for extended periods. The “social” here refers to the hosts rather than the parasites. Social parasitism is best known among the “cuckoo” bumble bees—subgenus Psithyrus—but also occurs in some halictines and allodapines. There is one species of bumble bee that has a normal colony cycle in most of its geographic range but becomes a social parasite in the extreme north.

In Bombus subgenus Psithyrus the female enters a nest and suppresses, or even kills, the host queen. The host’s workers then collect pollen and nectar and feed it to the parasite’s offspring. It is possible to identify Bombus (Psithyrus) females because they have lost the corbicula and the anterior surface of the metatibia is convex, dull, and hairy, whereas that of nest-building Bombus is a typical hind tibial corbicula—concave, shiny, and without hairs on the anterior surface except at the margins.

Socially parasitic allodapines are often difficult to distinguish from nest-building ones as they retain a reasonable scopa in some cases, perhaps indicative of a recent evolution of socially parasitic behavior.

Socially parasitic halictids of the genus Microsphecodes have been studied in detail in the field only once. Up to nine of the social parasitic females were found within a single host nest and up to 80 percent of the host brood was replaced by those of the social parasite.

See also Bumble Bees; Corbicula; Cuckoo Bees.

Spermatheca

Female bees (and those of most insects) store sperm after mating in a structure called a spermatheca. In bees, this is usually a somewhat spherical structure with a ring of tissue on one side looking a little like a toque—this is the spermathecal gland that secretes nutrients to keep the sperm alive. The spermatheca also has one or more sperm pumps that aid in pushing the sperm along the spermathecal duct to the vagina where one spermatozoon will fertilize an egg as it passes through. As a result of haplodiploidy, female bees can decide whether to produce a male or female offspring and they do this through nervous control of the sperm pump(s).

It is possible to tell whether a bee has mated through dissection. In an unmated bee, the spermatheca is like a clear glass ball. In a mated bee, there is at least a clump of opaque whitish or yellowish sperm inside the spermatheca. Social bees that must fertilize many eggs have a relatively large spermatheca to store larger amounts of sperm. In Lasioglossum marginatum, the sperm are packed so tightly inside the spermatheca that upon being prodded the spermathecal wall comes away, leaving a solid ball of sperm, like removing the tissue around an expensive citrus fruit at the market.

See also Eusocial; Ovaries, Ovarioles, and Oocytes.

Squash Bees

In much of North America, gardeners who grow zucchini or other squash can see hoary squash bees (Xenoglossa pruinosa; Apidae) tumbling in and out of their squash flowers early in the morning. These bees are excellent pollinators of squash and will visit no other flowers for pollen. Both sexes also feed on nectar from the male flowers of squash plants in which each flower is either a male or a female but individual plants will usually produce flowers of both sexes, though perhaps not simultaneously.

The most widespread species of Xenoglossa, the hoary squash bee, has an interesting history. It originated in Central America, where squash plants were first domesticated. As the cultural practice of growing squash for food spread to North America, the hoary squash bee followed: an intriguing counterexample to the observation that agricultural practices are often detrimental to wild bees.

There are around two dozen species of squash bees in the genus Xenoglossa with two-thirds of them belonging to the subgenus Peponapis. All but one species feed on various types of Pepo and its cucurbitaceous relatives.

See also Agriculture; Classification; Monophyletic; Pollination.

Stelluti

Francesco Stelluti (1577–1652) was a very talented man, a professional lawyer who was also well known for teaching and publishing in, among other things, mathematics and astronomy. He was also a poet and colleague of Leonardo da Vinci. He clearly was also a wise man: his Melissographia, from 1625, was the first publication to include illustrations of biological features drawn with the aid of a microscope, a full thirty years before the better-known works of Anton von Leeuwenhoek. Incidentally, the term “microscope” was also coined by him. As the name suggests, the subject of Melissopgraphia was bees and it featured three of them, in the same arrangement as on the coat of arms of the Barberini family, to whom the pope at that time (Urban VIII) belonged. Clearly, it was an astute move on Stelluti’s part to dedicate the book to the pope: at that time, nothing could be published without a papal seal of approval. Several years later he published a set of drawings showing the anatomy of the honey bee in greater detail as part of a book of the first translations into Italian of the poems of the Roman Persius.

See also Body Plan; Corbicula; Sting.

Stenotritidae

This is the smallest family of bees with only twenty-one described species. They are large, very fast, flying bees that are restricted to Australia where there are very few other bees similar in size. Stenotritids are short-tongued bees and a diagnostic feature of them is that their glossa is broadly rounded. This seems like an intermediate condition between the pointed glossa of most bees and the apically concave glossa characteristics of Colletidae. Indeed, it is now certain that the Stenotritidae are the closest living relatives of colletids and so the intermediate shape of their glossa may also have been an evolutionarily intermediate condition in the common ancestor of the two families. That said, the most recent common ancestor of the Stenotritidae is the youngest common ancestor shared among any of the bee families, suggesting that the lineage that led to extant stenotritids left no other descendants for about the first 50 million years of their evolution.

These large bees come in a range of colors and include one brilliant green and one yellow banded species. Most, however, are various shades of black or brown with hairs ranging from white, grey, and orange-brown, to black.

Stenotritids nest in the ground and none are known to share nests or possess any other form of social organization.

See also Biogeography; Classification; Mouthparts.

Sting

Bees are “known” to sting and that is one reason why they are considered rather scary by many and is the cause of some exaggerated claims on horror movie posters. But it is not true that all bees sting. Male bees do not sting because the sting is a modified egg-laying apparatus. Females in many lineages of bees have lost the ability to sting—in the case of fairy bees, for example, this may be because they are so small relative to the size of most of their predators that defense is useless. Other bees that have lost the ability to sting include the aptly named stingless bees—corbiculate relatives of honey, bumble, and orchid bees. These bees defend their nests by biting at sensitive body parts, although one genus secretes a “saliva” that burns skin, giving them their common name of “fire bees.” The reduced wing venation of stingless bees suggests that their ancestors may have been minute and perhaps they lost the ability to sting for the same reason as suggested for fairy bees. Another lineage of bees with complete loss of most sting-related structures are cuckoo bees in the megachilid tribe Dioxyini. It is a mystery why these bees do not sting as their bodies are robust and seem designed for defense. In contrast, the longest bee stings in relation to their body size can be found among some other lineages of cuckoo bee such as the nomadines Osiris and Coelioxoides.

What we normally think of as the sting is just the sting shaft, one part of a complex sting apparatus that includes seven other sclerites that are modified from the most apical metasomal segments. Honey bee workers lose the entire sting apparatus when they sting, along with the venom gland and associated musculature.

See also Meliponini; Venom.

Stylopids

Some stylopids are natural enemies of bees and they have one of the most unusual life cycles of any insect. The stylopid triungulin larva gains entrance into an adult bee’s body, where it develops on the nutrients inside the host. When fully grown, the male pupates and undergoes metamorphosis. Females, however, become adult while still looking like a grub. Males exit the body of the host, leaving a small hole or distorted margin to a tergum. Females remain attached to the host, with most of their body still on the inside but with their head and first few segments sticking out. The male locates a bee that has a female stylopid in it through olfaction, with pheromones detected with their unusual television aerial–like antennae. They then impregnate the female by passing sperm into a groove that runs along the side of her body (after all, her genitalia are on the opposite end of her body, deeply embedded within the host). The sperm then swim to her reproductive opening. She then develops fertilized triungulins internally, bypassing the egg stage, and the life cycle begins again.

Stylopids can have an effect on their hosts, and that is referred to as parasitic castration: males in particular take on some of the features of the opposite sex. For example, in bees where males have extensive pale markings on the face, stylopized males may have these markings reduced or absent.

The position of stylopids within the insect tree of life has been somewhat controversial, but it now seems certain that they are most closely related to beetles.

See also Beetles as Natural Enemies of Bees; Sexual Dimorphism.

Surface Sculpture

The surface of any body part of a bee is covered in what entomologists refer to as surface sculpture, though you need a microscope to see it. It takes on numerous forms on different body parts of the same specimen (even on different places on a single body part) and is often very important in species-level identification. There are two broad categories—microsculpture and macrosculpture. The former requires high magnification to see clearly but commonly takes the form of tiny scratches or overlapping minute plates looking somewhat like the tiles on a roof. Macrosculpture often takes the form of punctures—small to relatively large pits, like craters on the moon. Puncture size and density, in relation to the space between punctures, are highly variable, again often on different parts of the same individual. Other types of macrosculpture include striae, which are parallel linear features, or less regular patterns such as rugosity. Some raised patterns look somewhat net-like and are termed reticulate. Some parts of the bodies of some bees lack either micro- or macrosculpture and are often glassy-smooth and shiny as a result. Cuckoo bees often have strong sculpture to deflect stings or mandible of hosts away from their more sensitive body parts. In contrast, some cuckoo bee species have an integument that is smooth and shiny, perhaps making it difficult for offensive weapons to gain purchase.

The variation in appearance of both micro- and macrosculpture is endless and the terminology used to describe them extensive. Closely related species are often separated based on differences in the detail of their surface sculpture and this is often the only way to tell apart females of similar species; in the males differences in genitalia are often more useful.

See also Cuckoo Bees; Terminalia.

Tear-Drinking Bees

There are two groups of stingless bee that have changed the archetypal bee pattern of collecting pollen as a protein source for the next generation and both are found among the stingless bees. One group, currently best known from tropical Asia, are the tear-drinking bees. These obtain proteins from the anti-bacterial enzymes in vertebrate tears. There are three species, two of Lisotrigona and one of Pariotrigona. They have been photographed feeding at the eyes of turtles, chickens, eagles, and various mammals including, most extensively, the eyes of Hans Bänziger, who discovered the phenomenon. By baring his own eyeballs to the bees, Dr. Bänziger has found that some individual workers will return time and time again to obtain his lachrymal gland secretions. Some other meliponine species will sometimes feed at tears, often combined with lapping up sweat—an activity that has lead to some Meliponini being called “sweat bees,” though that name is perhaps best confined to the Halictidae. Tears, however, contain substantially more protein than does sweat.

Protein in tears is rather dilute, especially compared to its concentration in pollen. Thus, tear-drinking bees really need to drink a lot in order to obtain enough protein. Their metasomas become quite distended with all that liquid. As with the vulture bees, tear-drinking bees are generally not found to have pollen in their corbiculae.

See also Meliponini; Vulture Bees.

Telling the Bees

An ancient custom in parts of Europe is for beekeepers to inform their bees of important events such as births, marriages, or deaths, the belief being that if they are not given this information the bees may depart or the colony may not thrive. Especially if it is a beekeeper who has died, it is considered important that the bees be allowed a period of mourning. In some cases, this involved partially covering a hive with black cloth, in others raising it off the ground upon the beekeeper’s death and then putting it back to its original position as the coffin is lowered.

A possible origin of the idea is that, in some ancient cultures, bees were thought to mediate between the living world and the afterlife—and so telling them of a birth or death would seem beneficial. After a death, funeral cake would be offered to the bees as part of the “telling.”

The practice was made better known recently with the passing of Queen Elizabeth II. John Chapple, the Royal Beekeeper, informed the bees of the death of her majesty by knocking on each hive and then saying, “The mistress is dead, but don’t you go. Your master will be a good master to you.” Another recent reference to the practice is in the Outlander series, the ninth book of which has the title Go Tell the Bees That I Am Gone.

See also Apis; Hive.

Terminalia

The easiest way to tell closely related species apart is often by taking a quick glance at the male terminalia: the male genital structures. This often works even if the species are otherwise morphologically identical. Differentiation is aided by the complexity of these structures. In addition to the genital capsule—which itself is divided into a gonobase and a pair of each of a gonocoxa, gonostylus, volsella, and penis valve—they also include two hidden sterna (the seventh and eighth), which are remnants of segments that have been telescoped inside the metasoma. Any of these body parts, and often many of them, can be elaborated in complex ways. In some of the most morphologically monotonous groups of species, a single part can differentiate closely related species. Indeed, in the large genus Colletes, simple observation of S7—one of the two hidden sterna—is often sufficient to permit species-level identification. In other genera, some species may share a rather mundanely typical structure with no unusual embellishments, whereas others will have multiple parts considerably ornamented with crests, patches of long bristles, spines, and other rather bizarre modifications. Those with the simple genitalia and those with the elaborate ones look pretty much identical from the outside and are obviously closely related, but they would seem to be quite unrelated just from the study of their genitalia.

Unfortunately, using terminalia to identify specimens requires that these structures be extruded from the apex of the metasoma. This is relatively easy while the specimen is still soft, but if the bee is dead and dried it is necessary to soften it up by leaving it in a humid atmosphere at least overnight. The ensuing dissection may result in damage to the specimen, especially if the melittologist has shaky hands as a result of age, or too much caffeine.

See also Body Plan; Mating.

Urban

Danúncia Urban (b. 1933) is the foremost woman bee taxonomist in history with a publication record that spans more than sixty years. Based at the Universidade Federal do Paraná, Brazil, she worked all her career in the city of Curitiba, where she had been born. Throughout her career, she worked in close proximity to Padre Jesus Santiago Moure (1912–2010), who was the world authority on South American bees. She is best known for her work on long-horned bees—Eucerini and bees of the Anthidiini—describing twenty generic-level names among these groups. Even for some of the genera that she did not name, she was responsible for describing the vast majority of the known species. Of all the genera that she worked on, the panurgine genus Anthrenoides contains the greatest number of species described by her: over 60 of the 65 known species. Overall, she has described over 330 bee species.

Coming up with new names for many undescribed organisms can be rather challenging to a taxonomist. Urban was known to sometimes solve this issue by naming taxa after the person who walked by her office door at the time she was trying to come up with a new name. Consequently, many of the names she coined are based on the names of friends and colleagues: for example, Mirnapis after Mirna Casagrande, a lepidopterist; and Santiago from Padre Moure’s middle name. She enjoyed naming bees after people she knew. And this is a special gift that few receive.

See also Cockerell; Michener; New Species.

Usurpation

Whether it be an underground burrow or a tunnel excavated in a pithy stem or hard wood, constructing a nest requires a considerable expenditure of energy. It also causes wear and tear—mandibles of bees that have done a lot of excavation become bluntly rounded, sometimes being reduced to mere stubs. It is perhaps not surprising that there are individuals that do not perform all this work, but instead take over a conspecific’s recently constructed nest, sometimes making use of the food provisions the original nest maker collected and replacing the original owner’s eggs with their own.

It is possible to watch extended fights at the nest entrance where one large carpenter bee female is attempting to take over the nest of another individual. Usurpation also occurs interspecifically: giant resin bee (Megachile sculpturalis) females will take over the nests of the common North American large carpenter bee, for example.

One detailed study of Lasioglossum malachurus, a common European eusocial halictine bee, noted that there were bees that repeatedly tried to usurp nests of conspecifics during the spring solitary phase as foundresses were initiating their colony. Some were successful, but some were not. In this species, the nest entrances are plugged after the foundress has completed the production of a small worker brood. Once most bees in the aggregation had reached this stage, there were no open nests left to take over and so the unsuccessful potential usurpers had no option other than to construct their own nests.

See also Aggregation; Introduced Species.

Utah

Utah is commonly referred to as the beehive state. This appellation originated from the early Mormon pioneers who settled the area and started calling it the beehive state in the 1840s. Brigham Young wanted to call this area Deseret, the word for honey bee according to the Mormon bible. Being mostly a rather arid region, there was little that was found to sweeten the foods of the early settlers and so they imported honey bees from further east. Other reasons for them wishing to be associated with honey bees include the contention that the settlers worked as hard and were as industrious as honey bees, lived in efficient social groups as honey bees generally do, and that honey bees were mentioned both in the Bible and the Book of Mormon.

Instead of being named Deseret, the state ended up being named after the Ute, the indigenous occupants of much of the Great Basin who were almost entirely dispossessed of their lands in the 1850s.

Utah, as well as other areas, have geological formations called beehive rocks because of their similarity to the skep style of hive used by beekeepers until it was replaced by the Langstroth hive that is widely used today. While the rocks seem not to have been any part of the motivation for calling Utah the beehive state, the skep hive features on Utah’s state flag.

Utah’s nickname as the beehive state became official in 1959 but despite the name, it ranks near the middle of all the states in terms of honey production. Nonetheless, it is perhaps ironic that one of the largest bee collections in the United States is held in Logan, Utah.

See also Apis; Hive; Religion.

Venom

Bee stings are meant to be painful as they are defensive in function and anyone who has been stung will want to avoid repeating the experience. Bee venom contains hundreds of different peptides, the major component of which, melittin, is responsible for causing much of the pain. Another component dilates the blood vessels, increasing the spread of the venom. Deaths due to stings are rare and usually result from anaphylactic shock from an allergic reaction to an enzyme in venom that breaks down cell walls, although additional components of honey bee venom are also potentially allergenic.

Sting-related deaths are not generally collated according to the taxonomy of the stinging insect, so the data include deaths from hornets and other wasps as well as other bees. Data from Europe and the United States are remarkably similar, with 0.26 and 0.22 sting-related deaths per million inhabitants per annum, respectively. While the number of deaths is low, they represent 20 percent of the mortality resulting from anaphylactic shock. Diagnosing someone’s risk of anaphylactic shock from bee venom is not straightforward, but treatment through subcutaneous injection of small quantities of venom, termed “venom immunotherapy,” can reduce the risk of death from stings.

Some honey bee allergens are also found in the venoms of other stinging insects and cross-reactivity to being stung by a second species for the first time may elicit a stronger allergic response.

The numerous touted beneficial effects of venom, besides venom immunotherapy, are not all well demonstrated. The best known is as a treatment for rheumatism. However, apitherapeutic uses of venom have not usually been subject to rigorous controlled experiments, while the dangers of getting stung are well known.

See also Sting; Warning Coloration.

Vision

Bees see the world differently than we do. First, like almost all insects, their compound eyes are made up of numerous facets that are wired up in such a way that edges of features are emphasized. This means that they can easily detect moving objects, such as predators, and escape a melittologist’s approaching net. Their color vision is also different from ours; they cannot see red as a color—they perceive it as black, but they can see further toward the ultraviolet end of the spectrum. Thus, red flowers are not usually attractive to bees—though they may be visited by butterflies and birds, which see further into the red end of the spectrum. Despite this, there are some bees that specialize in red flowers such as those of some cacti.

Because of their ability to see ultraviolet, flowers often look remarkably different to bees than they do to us. For example, many relatively round flowers that look uniformly yellow will look like a bull’s-eye to a bee, with the pattern caused by the presence or absence of ultraviolet in rings leading the bees to the center of the flower. Flowers with more complex structures may have lines of ultraviolet color that point toward the nectar.

See also Nectar.

Vulture Bees

There is a group of three stingless bee species in the tropical western hemisphere that are obligate necrophages: their protein requirements are met from the bodies of dead animals, and they do not collect or store pollen. These bees, species of the Trigona necrophaga group do, however, store honey, which has been described as “of good” or “agreeable” flavor. The brave melittologists who risked their health to savor the honey of carrion-feeding bees are to be saluted!

Vulture bees chew flesh from a dead animal—a wide range of dead vertebrates as well as earthworms or toad eggs. They have also been observed consuming larvae from abandoned social wasp nests where they act as predators rather than necrophages. The protein sources are transported back to the nest in the bee’s crop, regurgitated into pots that remain open for less than a day before being sealed. Consequently, their corbicula is considerably reduced. Honey is added to the proteinaceous mixture, which likely aids in preventing spoilage of the animal-derived materials. The contents of the sealed pots mature for two weeks resulting in chemical simplification and an increase in the sugar and amino acid concentration of the food that is then fed to developing larvae.

Some vulture bees aggressively chase away carrion flies at carcasses. They can turn a dead vertebrate into a skeleton in a few days through recruitment and cooperative foraging with later arrivals using the hole chewed through the skin by earlier bees to feed on the inside of the carcass.

See also Tear-Drinking Bees.

Warning Coloration

While many organisms are camouflaged or hide away so that predators do not notice them, there are many that are brightly colored as if advertising their presence. In many cases, these bright colors serve to warn predators that this potential prey item will fight back—either actively, such as by stinging, or passively, such as by tasting disgusting. The bright colors of bumble bees and many others serve to warn that the bee will sting. Bees sting so quickly that it is quite likely that they will be released by a predator undamaged. Though even if the bee is fatally hurt there is still a benefit—as the predator will undoubtedly avoid repeating the experience and so avoid insects that appear similar in the future. As many of these will be relatives of the damaged or deceased bee, it gains benefit through kin selection. Bees reinforce the visual experience with an auditory one—the buzz they make when irritated. It is no surprise that buzzing sounds are often perceived as scary by most people, even adult melittologists in moments of weakness.

Warning coloration is any pattern that stands out against the background. Stripes of white, yellow, orange, or red against a black background, or combinations of those colors, are the common ones found among bees. Black with a red tail is another common warning pattern.

Predators can learn to avoid warningly colored potential prey items, but they may also be innately prone to avoiding certain colors or patterns as natural selection will favor predators that completely avoid being stung.

See also Integumental Coloration; Kin Selection; Mimicry.

Wasps as Natural Enemies of Bees

While bees arose from among the wasps, there are wasps that have subsequently evolved to be natural enemies of bees. Most famous of these are the bee wolves (Philanthus, family Philanthidae) that paralyze several bees and store them in a brood cell as food for each of their offspring. One species concentrates on the western honey bee, another on bumble bees, but most are not so specific, attacking any bee of suitable size and even sometimes including other wasps or even an ant or two. These wasps are quite closely related to bees, but the other wasp enemies of bees are more distantly related.

One type that has recently received attention is the oriental hornet (Vespidae), which is a predator of honey bees. The foraging adults will invade a honey bee nest, stealing adults from the entrance or brood from inside. Honey bees in areas where these wasps are native—South East Asia—have several defense mechanisms including “shimmering,” where the adults of non-cavity nesting species do a rapid entomological version of the sports-stadium Mexican wave aimed at scaring the wasp away.

Bees that nest in twigs or other cavities are particularly susceptible to a range of wasp enemies. Grotea are ichneumon, or Darwin, wasps (Ichneumonidae) with long thin bodies and long thin ovipositors that can reach through the nest entrance to lay eggs inside the host nest in the stem. These wasps are often larger than single hosts and thus seem to require two or more bee larvae to complete their development. Some chalcid wasps are tiny parasites of bees with multiple wasp larvae developing within a single bee host. Velvet ants (family Mutillidae) attack a wide range of ground-nesting bees and wasps, with one species attacking bumble bees and a few with orchid bees as hosts. The velvet ant larvae are ectoparasites, feeding on the outside of the host larvae or pupae.

See also Beetles as Natural Enemies of Bees; Flies as Natural Enemies of Bees.

Wasps as Relatives of Bees

The insect order Hymenoptera is commonly referred to as the ants, bees, and wasps. We should also add the sawflies, which make up the earliest, mostly vegetarian branches within the order. Sawflies differ from other Hymenoptera in lacking the “wasp waist”—the narrow junction of meso- and metasoma. Most of the species that possess the narrow waist are parasitic wasps such as chalcids, ichneumon “flies” (also called Darwin wasps), and braconids of which there may be millions of species, the vast majority of which have yet to be described. Stinging Hymenoptera—which includes ants, bees, digger wasps, yellowjackets, and their relatives—have turned the ovipositor of the parasitic wasps into a weapon for paralyzing prey or defending the bearer (or its colony). The glands that lubricated the ovipositor to ease passage of the egg have evolved to produce a paralytic venom to immobilize prey. The term “wasp” could apply to all these stinging and parasitic wasps. Thus, both ants and bees are merely relatively easily recognized (perhaps) types of wasp.

Bees arose within a particular group of wasps—now somewhat circularly termed apoid wasps. These include digger wasps, thread-waisted wasps, and organ-pipe wasps as well as bee wolves. It used to be thought that bees and these wasps were sister groups, but it is increasingly clear that bees arose from deep within apoid wasp evolution. It seems that the closest relatives of bees are tiny thrips-hunting wasps. Considering that thrips can often be found in flowers, perhaps the switch from hunting tiny insects in flowers to collecting tiny pollen made by flowers was a relatively easy one. Either way, if this innovation had not happened, the world would be a very different place.

See also Body Plan; Classification.

Wax

Beeswax is produced by worker honey bees to form the comb in which honey is stored and brood reared. It is produced by glands in the metasomal venter each of which will produce a transparent wax scale that becomes colored as a result of being chewed and the incorporation of other hive constituents. It is biochemically produced from honey with a production ratio of about 7 kilos of honey for 1 kilo of wax. In turn, the bees can use 1 kilo of wax to store over 20 kilos of honey.

Beeswax has numerous uses for people, among which candles are the best known. Candles have been made from beeswax for perhaps thousands of years and it is the preferred source for them because it burns brightly without producing smoke. Other ancient uses include in lost-wax casting and as a dental filling, both known from the Neolithic period, over six thousand years ago. Among other well-known uses are as a sealant, surface protectant for some fruits, in stamped seals for letters, and moustache sculpting. Some perhaps surprising uses include to absorb oil spills from water, in surgery to prevent bleeding from bones, as a lubricant for bullets in some firearms, and in making bows and stabilizing reeds in string and wind instruments, respectively.

See also Apis; Propolis.

Wax: Or the Discovery of Television among the Bees

This rather surreal movie (as is suggested even by the title) was first released in cinemas in 1991, and in 1993 became the first movie to be streamed on the internet. It was also one of the first sites on the World Wide Web, where it was called “Waxweb” and available in an interactive format. It became something of a cult hit and won several “top 10 movies of the year” awards.

Director David Blair is the narrator and lead actor, playing the role of Jacob Maker who works as a computer code developer for target acquisition programming at the Alamogordo weapons development base. Beekeeping is his passion and he had inherited his “Mesopotamian bees” from his grandfather James “Hive” Maker—played by William S. Burroughs (1914–1997). Jacob wears his beekeeping suit even when at work and during long walks in the New Mexico desert. On one such walk, bees enter his head, enabling him to see bee television where the past and the future combine. The dead of the future, the story of Cain and Abel, the Garden of Eden (entered through a cave), the Tower of Babel, the development of the nuclear bomb, the Trinity nuclear test, and the first Gulf War are recurrent themes, and the film was, in fact, an early critique of that war.

The astronomer Clyde Tombaugh (1901–1997, the discoverer of Pluto) also makes a brief appearance (as himself).

See also Cartoon Bees; Hive; Sculpture.

Wing Veins

Unlike butterflies and moths with colorful patterns of scales on their wings, bee wings are usually translucent: although they are sometimes smoky, orange, or shades of metallic green, blue, or purple, they are rarely patterned. Wings are made of membranes that are strengthened by tubular wing veins that usually stand out as brown lines against the background. The pattern of the veins and the shape of the cells they subtend is extremely important in bee classification and identification.

On the anterior margin there is usually a somewhat semicircular structure that is broader than the veins; this is called the stigma. Whether a bee has an obvious stigma or not, and its size relative to other nearby structures, is an important characteristic. The marginal cell, situated beyond the stigma, varies in how long it is, whether its apex is bent away from the anterior margin of the wing, and whether this apex is acutely pointed, rounded, or truncate—all features used to help identify different groups of bees. The submarginal cells are located behind the stigma and marginal cell and whether a bee has two or three of them (rarely there is only one or none at all) is an important feature because in most groups the number is evolutionarily conserved. For example, all Megachilidae except the earliest diverging genera have two submarginal cells but all corbiculate bees other than the stingless bees have three. But there are some genera and even species in which the number varies. Rarely an individual may have two on one forewing and three on the other. A unique individual of a turret bee (Melitoma, Apidae) had four submarginal cells on one forewing with the normal three on the other.

See also Body Plan; Classification.

Worker

Bees with a reproductive division of labor—as in semisocial and eusocial societies, have both queen and worker castes: with the difference between them mostly in terms of direct reproductive output. As in social wasps and ants, worker bees are all female. Workers are responsible for continuing expansion of the nest, defense of the colony, and collecting food for the queen and the brood. With so many tasks requiring attention, many advanced social insects have further division of the workers into subcastes—such as the soldiers, porters, and standard workers in army ants. Bees do not have such extensive morphological diversity within a colony, although defensive guards may be slightly larger than their nestmates and workers may have temporally distinct tasks. In honey bees, the young workers stay in the nest and transfer food to the developing brood while it is the older ones that do the more dangerous activity of foraging outside the nest. Some individuals may have even more specialized tasks with some behaving as undertakers, looking for and ejecting deceased nestmates.

Worker honey bees are also unusual among all bees in that the act of stinging eventually results in their death. The sting has barbs that are much better developed than those of other bees and the entire apparatus, including the venom gland, is pulled out of the body as the bee flies away with the sting shaft hooked into the victim. In the period between evisceration and death, these bees further defend the colony by flying closely around the enemy and buzzing loudly.

See also Apis; Eusocial; Queen; Sting; Venom.

Xeric Environments

It has long been known that bee diversity is greatest in rather dry habitats. The Southwest of the United States and adjacent Mexico, the Mediterranean and Central Asia, Southern Africa, Central Chile, and much of Australia are home to a disproportionate diversity of bees both in terms of bee phylogeny and the number of species. For example, Israel has almost a thousand bee species while the Democratic Republic of Congo has less than two-thirds that number despite being over a hundred times larger. This pattern of species richness is not matched by the number of flowering plant species: there are three times as many in the tropical country compared to the Middle Eastern one. Why are bees comparatively diverse in arid environments?

There are two broad approaches to answering questions like this. If bees arose in dry habitats, they would have had more evolutionary time to diversify in them. Alternatively, perhaps speciation rates are higher in arid areas and / or extinction rates lower. It is thought that bees originated in arid environments, but it also seems possible that their rate of speciation is higher in areas with unpredictable rainfall. There is a higher proportion of oligolectic bee species in arid habitats, likely because bees do better if they can cue-in to the same weather patterns that result in their preferred host coming into bloom (and it is known that each arid land flower species has its own cues for flowering). Another advantage to bees nesting in dry areas is that their pollen balls are less likely to succumb to mold.

See also Biogeography; Oligolectic.

You Can Help the Bees

With numerous threats causing declines in populations of many bees, we can all do something to help them. Some threats are beyond solution by individuals, such as climate change and habitat destruction. But we can all communicate our irritation at these developments to politicians from local to national levels. Pesticides have negative impacts on bees, and we can attempt to reduce their use both personally by buying organic food and not using them in our own gardens as well as by promoting pesticide-free farming to policy makers.

There are also practical actions that can be taken in the backyard such as planting flowers (and flowering trees) that are easy for wild bees to obtain food from: these are plants and trees with flowers of a relatively simple structure. Providing suitable nest sites for bees by, for example, leaving pithy stems such as raspberry canes in place the following year will help stem-nesting bees. Leaving some patches of bare soil in the garden and / or not digging or tilling very deeply will help most ground-nesters: very few bees choose lawns as a nest site.

One thing that does not help wild bees is increasing the number of honey bee hives in an area. Despite many “bee city” initiatives promoting honey bees, their massive colonies have been shown to negatively impact wild bees through both competition for resources and spreading disease. It is also worth remembering that the domesticated honey bee that is in use almost worldwide is native to Africa and Europe and is an introduced species in the western hemisphere and Australasia. “Saving the bees” through increasing honey bee populations is like saving songbirds by raising chickens. That said, beekeepers are often great promoters of wild bees and / or the flowers that feed them.

See also Apis; Citizen Science.

Zacosmia

Zacosmia is a cuckoo bee belonging to the nomadine tribe Melectini. The genus is monotypic and its single species, Z. maculata is found through much of the western United States and the extreme southern prairies of Canada. Maculata is a good species name for this bee because of its mottled appearance: it is attractively patterned, mostly in cream and shades of brown. The darkest brown is the underlying integument and the paler markings are made by hairs. The mesosoma is mostly dark with pale markings while the metasoma is mostly pale with dark markings. The legs are reddish-brown with patches of pale hair. Even the wings are mottled, with the apex dark—a feature that occurs in some other bees. What is less common are the dark spots in the second submarginal and marginal cells found in Zacosmia.

It is perhaps the smallest member of its tribe and, appropriately, its hosts are small species of Anthophora (Apidae), those belonging to the subgenus Micranthophora. Like other members of the Melectini, Zacosmia attacks host brood cells that have been completed and it seals the opening it makes in the brood cell with soil. Its larvae are hospicidal.

See also Cuckoo Bees; Hospicidal.

Acknowledgments

Books like this would not be possible without the hard work of melittologists of the past and present. I would particularly like to thank the late George Eickwort, Charles Michener, and Fernando Silveira and the living John Ascher, Stephen Buchman, Bryan Danforth, Sam Droege, Bob Minckley, Cecile Plateaux-Quénu, and Jerry Rozen. For helpful review of and / or inspiration for and / or assistance with one or more entries, I thank Hans Bänziger, Cecily Bradshaw, Sheila Colla, Esteban d’Bzi, Jessie Huisken, Aline Martins, Sandra Rehan, James Rolfe, Michael Schwarz, Cole Swanson, John Wenzel, Amro Zayed, and two anonymous reviewers. I am grateful to Robert Kirk for the opportunity to write this book and to Megan Mendonça for administrative assistance. For help during writing, I thank Daniel, Laurel, Lynn, and Paul Quesney and Marie-Pierre Lahalle; and as always, I would likely achieve none of this without the love and support of Gail Fraser.

Further Reading

Danforth, B. N., Minckley, R. L. and J. L. Neff. 2019. The Solitary Bees: Biology, Evolution, Conservation. Princeton, NJ: Princeton University Press.

Michener, C. D. 1974. Social Behavior of the Bees. Cambridge, MA: Harvard University Press.

Michener, C. D. 2007. The Bees of the World. Baltimore: John Hopkins University Press.

Packer, L. 2010. Keeping the Bees. Toronto: Harper Collins.

Packer, L. 2023. Bees: A Guide to Every Family. Princeton, NJ: Princeton University Press.

Classification Table for Bee Taxa Mentioned in the Text       (see also the associated phylogeny)

Family

Subfamily

Tribe

Genus/Species

Common Name

Short-Tongued Bees

Andrenidae

Andreninae

Andrenini

Andrena

Solitary mining bees

Andrenidae

Oxaeinae

Andrenidae

Panurginae

Perditini

Perdita minima

A fairy bee

Andrenidae

Panurginae

Protandrenini

Anthrenoides

Colletidae

Callomelittinae

Colletidae

Colletinae

Colletes hederae

The ivy cellophane bee

Colletidae

Diphaglossinae

Colletidae

Euryglossinae

Colletidae

Hylaeinae

Hylaeus pectoralis

A masked bee

Colletidae

Neopasiphaeinae

Cladocerapis bipectinatus

Colletidae

Neopasiphaeinae

Lonchopria

Colletidae

Neopasiphaeinae

Nesocolletes

Colletidae

Scrapterinae

Colletidae

Xeromelissinae

Xeromelissa

Halictidae

Halictinae

Agapostemonini

Agapostemon virescens

The bicolored agapostemon

Halictidae

Halictinae

Augochlorini

Megalopta

Halictidae

Halictinae

Halictini

Lasioglossum malachurum, L. marginatum

Halictidae

Halictinae

Sphecodini

Microsphecodes

Halictidae

Nomiinae

Nomia melanderi

The alkali bee

Halictidae

Nomiinae

Pseudapis

Halictidae

Nomioidinae

Halictidae

Rophitinae

Systropha

Spiral-horned bees

Melittidae

Dasypodainae

Dasypoda

Pantaloon bees

Melittidae

Meganomiinae

Melittidae

Melittinae

Macropis, Rediviva

Long-legged bees

Melittidae

Melittinae

Melitta

Stenotritidae

Long-Tongued Bees

Apidae

Anthophorinae

Anthophora

Flower bees

Apidae

Apinae

Apini

Apis cerana

The eastern domesticated honey bee

Apidae

Apinae

Apini

Apis dorsata

A giant honey bee

Apidae

Apinae

Apini

Apis florea

A dwarf honey bee

Apidae

Apinae

Apini

Apis mellifera

The western domesticated honey bee

Apidae

Apinae

Bombini

Bombus (Psithyrus)

Cuckoo bumble bees

Apidae

Apinae

Bombini

Bombus dahlbomii, B. wilmattae

Bumble bees

Apidae

Apinae

Euglossini

Eufriesea

Orchid bees

Apidae

Apinae

Euglossini

Euglossa

Orchid bees

Apidae

Apinae

Euglossini

Eulaema

Orchid bees

Apidae

Apinae

Meliponini

Cleptotrigona

Robber bees

Apidae

Apinae

Meliponini

Lestrimelitta

Robber bees

Apidae

Apinae

Meliponini

Lisotrigona

A stingless bee

Apidae

Apinae

Meliponini

Oxytrigona

Fire bees

Apidae

Apinae

Meliponini

Tetragonisca angustula

A stingless bee

Apidae

Apinae

Meliponini

Trigona necrophaga

A vulture bee

Apidae

Eucerinae

Ancylaini

Ancyla

Apidae

Eucerinae

Emphorini

Melitoma

Turret bees

Apidae

Eucerinae

Eucerini

Canephorula apiformis

Apidae

Eucerinae

Eucerini

Eucera longicornis

A longhorned bee

Apidae

Eucerinae

Eucerini

Mirnapis

Long-horned bees

Apidae

Eucerinae

Eucerini

Santiago

Long-horned bees

Apidae

Eucerinae

Eucerini

Xenoglossa pruinosa

The hoary squash bee

Apidae

Eucerinae

Exomalopsini

Exomalopsis

Apidae

Nomadinae

Melectini

Zacosmia

Apidae

Nomadinae

Osirini

Osiris

Apidae

Xylocopinae

Allodapini

Hasinamelissa

Reed bees

Apidae

Xylocopinae

Ceratinini

Ceratina hieroglyphica

A small carpenter bee

Apidae

Xylocopinae

Ctenoplectrini

Ctenoplectra

Apidae

Xylocopinae

Xylocopini

Xylocopa

Large carpenter bees

Megachilidae

Fideliinae

Megachilidae

Megachilinae

Anthidiini

Anthidium porterae

A wool carder bee

Megachilidae

Megachilinae

Anthidiini

Dianthidium macrurum

The long-tailed giant pebble bee

Megachilidae

Megachilinae

Anthidiini

Stelis

Megachilidae

Megachilinae

Dioxyini

Megachilidae

Megachilinae

Megachilini

Megachile pluto

Wallace’s giant resin bee

Megachile rotundata

The alfalfa leafcutting bee

Megachile sculpturalis

The giant resin bee

Megachilidae

Megachilinae

Osmiini

Osmia

Orchard bees