Bees
Bees descended from wasps which decided over 150 MYA that provisioning with sweet nectar and protein-rich pollen from flowers beat hunting other insects. Subsequent coevolution with angiosperms resulted in radiation which begat ~20,000 extant bee species.
Bees are classified into 9 families, which are divided into 3 broad groups, based upon average tongue (proboscis) length. Shorter-tongued bees tend be more ancient: more reminiscent of their carnivorous wasp ancestors. By contrast, long-tongued bees are more specialized to the floral-foraging lifestyle. Bumblebees and honeybees are this group.
Irrespective of tongue length, bees vary in their sociality. Some are solitary, whereas others, such as honeybees, are eusocial.
Not all bees are solely into nectar and pollen. ~450 bee species prefer floral oils for larval food and nest construction; a resource provided by ~2,000 distinct plants. Oil-collecting bees are in the most ancient families.
Honeybees
The combination of cooperation and division of labor bestows a tremendous advantage upon the social insects. ~ American entomologist Bert Hölldobler & American sociobiologist Edward O. Wilson
Honeybees descended from tropical Asian bees that nested in cavities. 300,000 years ago they swiftly spread across Europe and Africa. Honeybees were brought to the Americas in the 17th century by Spaniards who called honey “liquid gold.”
Although honeybees are ostensibly tropical, the genus has proven to be extremely adaptable generalists. Only 7 species of honeybee are recognized, albeit with over 44 subspecies.
Though other bees produce and store honey, only honeybees build wax nests, which are commonly called hives.
Honeybee colonies are the apex of bee civilization. But all bees are builders. Osmia avosetta, a solitary mason bee native to the Levant, builds her 1-cm long, cocoon-like brood chambers out of flower petals she has collected and glued together. For insulation and integrity, the initial flower-petal layer is lined with mud, which is then covered over in another, interior layer of flower petals.
The ecological importance of honeybees cannot be overstated. 80% of all flowering plants are pollinated by insects; of these, 85% by honeybees. 90% of fruit trees depend on honeybees for their pollination. The foragers of a honeybee colony may visit several million flowers on a single workday.
The social structure and life cycle of a honeybee hive is well known. A single queen breeds for a colony filled with females.
A hive may have 100,000 members. The larger the population, the more efficacious the foraging – economy of scale. Bees in large colonies are efficient food finders, mobilizing foragers to productive flower patches much quicker than in smaller hives.
A honeybee hive is a huge sorority. Honeybees only start to produce brood cells for males (drone comb) when colony size reaches 4,000. How a hive knows its population count is not known.
Drones are made and tolerated only when colonies can support them and when virgin queens of other colonies are anticipated. (The timing and extent of drone production is controlled by many of the same factors which influence the decision to swarm.) Drones spend most of their time at mating sites teaming with hundreds or thousands of other drones, competing for the favors of the few gynes which show.
To avert the perils of inbreeding, bees tend to nest near one another. A sizable hive may host 200–300 drones (males) during the summer breeding season.
Drones’ only role is to inseminate virgin queens of other colonies. A drone takes 3 seconds to ejaculate before its penis is ripped from its body; upon which, writhing in pain, it dies.
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Honeybee colonies are complex societies, with a vast variety of tasks needed to maintain a hive. Too little diversity could threaten colony survival. Yet honeybees have only 1 queen; so she takes precautions.
In prelude to founding a colony, a queen will mate with as many males as are available. 2 dozen drones is typical, allowing a new queen to store 7 million sperm.
This polyandry results in a healthier hive, as the queen acquires probiotic bacteria from her sexual encounters. Her microbiota are propagated throughout the colony.
Multitudinous mating serves another, veiled purpose. It fosters societal stability.
Workers in nearly half of yellow-jacket wasp colonies eventually revolt against their queen. They do so because the queen had only 1 mate, making workers less closely related to the queen’s sons than ones that they would produce. Workers want males more closely related to them, so they overthrow the queen and produce their own drones.
The other technique that engenders variation among honeybee workers is genetic recombination, to mix traits, and engender diversity in the colony. Honeybee recombination rates are higher than any other animal; more than 20 times that of humans. Honeybee workers don’t know how related they are to their coworkers. This ignorance fosters social cohesion.
Emergency queen selection presents workers with an opportunity to select full- (0.75 relatedness), rather than half- (0.25 relatedness) sisters as new queen candidates. ~ American entomologists James Withrow & David Tarpy
When a queen suddenly totters, instead of promoting “supersister” larvae that are more closely related, workers select “royal” larvae as candidates to become the new queen. Rather than be selfish, workers look to the good of the hive in maintain diversity.
Nepotism is overridden by favoring cooperation and altruism. ~ James Withrow & David Tarpy
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In various behaviors and overall level of discipline the personality of a honeybee colony reflects that of the queen. Workers of course also have their own personalities.
Hive personality can make the difference whether a nest survives the winter. A colony lacking disciplined diligence is at risk. No species illustrates the importance of leadership like honeybees.
Life Cycle
A queen bee lays just 1 pearly-white egg into each brood comb cell. (The brood cells of queens-to-be are separate from those of workers.) A goodly portion of yolk is laid into the cell prior to the egg. The queen glues the egg to the floor of a cell.
After 3 days the eggs hatch into larvae: tiny wormy creatures as white as snow. (72 hours is average. Incubation time varies from ~44 to ~144 hours.) All other insects hatch from their eggs by rupturing the egg membrane. Honeybee egg membranes uniquely dissolve during eclosion (hatching from the egg).
Nursing larvae is an intensive mothering. Nurse bees make ~10,000 visits to each larva during its development.
Larvae are fed by nurse bees from special glands in their heads which produce bee milk: a milky-white liquid which is the honeybee equivalent of mother’s milk. To produce this food, nurses must gorge on protein-rich pollen.
Bee milk which is deposited in gyne (larval queen) cells is called royal jelly. The protein royalactin in royal jelly engenders development of a queen via epigenetic modifications.
Brood food refers to any food provided to growing larvae, including bee milk/royal jelly and other foodstuffs. Whereas brood food may be placed in more spacious gyne cells, worker and drone larvae are always fed directly.
The food given to larvae depends upon their age and caste. All larvae are fed mainly bee milk for a brief period in early development. Only gyne are extensively fed royal jelly throughout the larval stage.
All larvae are vaccinated against local pathogens. The vaccine, in the form of a bee blood protein, is put into brood food.
Whereas queenly larvae consistently receive a diet rich in proteins and sugar, the brood food of worker larvae changes during development. To rapidly gain weight, young worker larvae get a rich diet. Older larvae require less protein; instead needing a high-sugar diet to complete development.
Bee milk is mixed with crop contents in specific proportions for proper nutritional value, depending upon development stage and caste. The mixture of bee milk, honey (or nectar), and pollen given older worker larvae is sometimes called bee bread.
Larvae tell their caregivers what they want to eat via pheromones, which waft through the hive. Foragers adjust their harvests based upon these chemical communiqués.
Workers recognize larval age by detecting changes in the pheromones emitted by larvae as they mature and adjust the foraging division of labour (pollen versus nectar) to meet the nutritional needs of the colony’s brood. ~ American entomologist Kirsten Traynor et al
After 6 days, worker larvae spin their cocoons and pupate: mummies in the privacy of their capped cell.
(Developing bees undergo 6 molts, during which the exoskeleton is shed. 5 of these occur during larval development. The last happens when a bee emerges as an adult.
The final larval molt is the metamorphosis into a pupa. Prepupal larvae begin to look like adults just before the cuticle is shed. Following the molt, as a pupa, the adult bee form is obvious.
To spin a cocoon, a larva uncurls, stretching out fully within its cell, with its head towards the capped end. The cocoon is mostly secreted silk from what will become salivary glands in adults. Also mixed in is feces. A larva defecates early during cocoon construction, having been unable to do so during its larval feeding, as it had no outlet. The feces provide pupal casing material.)
The cell is capped at the proper time by workers tending the larvae. 12 days later adult bees chew their way through the wax cap, ready to join the hive. (Under normal colony conditions, brood mortality is low: over 90% of the eggs laid live to adulthood.) Whereas workers go from an egg laid to a bee in 21, queens develop in 16 days, while drones take 24 days.
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Worker bees live only 6 weeks. A queen may live for 3 years, eventually worn out from laying a prodigious 1,000 to nearly 2,000 eggs a day, depending upon the season. A queen lives for the continuance of the hive, relentlessly laying 500,000–750,000 eggs in her lifetime.
King Bee
Conformant with the ways of the human world, the large bee heading the hive was thought to be a king well into the 17th century.
The king bee never leaves the hive, either for food or any other purpose, except with the whole swarm. ~ Aristotle
As early as the 300s (6 centuries after Aristotle), writers were mentioning the “mother bee.” Despite the descriptor, she wasn’t really running anything – she was too busy laying eggs. The idea of a female leading any animal society seemed absurd.
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6 to 10 young bees, usually less than 12 days old, constantly attend the queen, grooming and feeding her rich royal jelly, which includes an immune-system booster.
Colonies grow in size as long as floral resources support them or until a queen falters.
The queen secretes a pheromone which suppresses ovulation in the ovaries of workers and prevents them from rearing new queens. Workers frequently lick the queen. In offering food to other workers, the queen substance pheromone is passed around the brood chamber.
Colony business as usual lasts only as long as a queen keeps doping the colony. It is an honest signal of a queen’s productivity, which is essential to hive survival.
Workers replace queens when they weaken. (Supersedure tends to happen in the late spring or early summer, though may occur anytime from early spring through autumn.) Within an hour or 2 of a queen becoming ill or dying, workers in the brood area initiate changes to usher in a new regime: constructing queen cells for the youngest larvae, who are fed royal jelly throughout their larval lives, thus destined to eventually fight each other for the role of queen.
The entire process from queen loss to a new queen regime may take nearly a month. In the meantime, the old queen continues to lay eggs if she is able, and often is not eliminated until a successfully mated new queen begins her own egg-laying. The tolerance of the old queen is a hedge: ensuring an egg-layer in the event a virgin queen fails to return from her mating flight.
As colonies grow, the dilution of queen substance below a critical threshold is a factor that can lead to hive division by swarming. A 2nd queen is born into the hive. She takes thousands of her followers to another residence as the sky buzzes with bees. Having been informed by scouts of possibilities, the queen has her own criteria for what constitutes a suitable nest.
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Almost all feral colonies swarm sometime in the spring. Up to 40% of the swarms which successfully establish new nests will swarm again, causing a secondary peak in swarming at the end of the summer. ~ Canadian entomologist Mark Winston
Swarming is a well-timed and coordinated activity involving thousands of individuals, albeit centered upon queen rearing. The decision to swarm depends on several factors, though resource abundance is a primary stimulus.
Honeybees evolved in the tropics and expanded into temperate biomes, where winter’s chill takes a toll. Obviously optimists, as evidenced by their entrepreneurial swarming, honeybees may push themselves beyond their limits.
Many colonies in temperate climates do not survive the winter; most starve to death. ~ Mark Winston
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Honeybees are altricial. Being well taken care of as a larva is essential to a honeybee becoming a productive member of the colony. Workers look after each other.
A worker typically performs a variety of primary tasks through her life, taking on new roles as she ages. Task assignment is also a matter of inclination and capability. A relative few workers stick with the same task for much of their lives, such as grooming other workers.
Worker bees are both generalists and specialists. Any one job such as cell cleaning, brood tending, or foraging is highly specialized, yet a typical worker will perform many of these specialized tasks within the space of a few hours, and perhaps 15–20 such tasks during her lifetime. ~ Mark Winston
Young workers tend to work in groups, keeping the hive clean and acting as nurses to the next generation: tending developing brood and capping off older larvae as they enter pupation. During the 2nd week of adulthood, while some bees move to tending the queen, others patrol the hive for any abnormalities in eggs or larvae.
Older workers influence younger workers. ~ American entomologist Rachael Kaspar
After a worker’s royal jelly gland atrophies from age, within a very few days, a worker may move on to building comb cells. There are other career changes as life progresses, and to meet the needs of the nest: receiving pollen and nectar from foragers or guarding the hive.
For some in their 2nd week of adulthood, orientation flights outside the hive begin for apprentice foragers. Within a few days, a young bee graduates to full-fledged forager.
This general sequence may be modified to fit the needs of the colony, which varies depending on the flower crop, temperature, colony age, and other factors. Wide-scale worker coordination is possible because of honeybees’ sophisticated languages and superior sociality.
Workers adjust their temporal division of labor schedules in response to a broad range of nest and external environmental conditions. These adjustments provide a flexible caste system exquisitely tuned to colony requirements. ~ Mark Winston
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Honeybees forage for pollen, nectar, and resins. Pollen and nectar are collected from flowers. Honeybees switch their foraging focus between nectar, pollen, and the ingredients for propolis depending upon immediate colony needs.
Pollen seems practically weightless, yet an average honeybee colony collects 30 kg of pollen over a flowering season.
As nectar is 70% water, it has heft. A beehive takes in 60–1,600 kg of nectar a year, producing half as much in honey.
Per volume, resin is a modest part of the harvest, but it is quite important. Some resin comes from blossoms, but most comes from buds, fruit, or leaves. The resin is used to produce propolis: an invaluable substance to bees as both medicine and for home repair.
Honey
Food exchange among workers is at the heart of the social system of these insects. ~ American entomologist Charles Michener
A honeybee sucks the nectar from a flower using her proboscis, storing it in her honey crop, a specialized organ in the foregut. When a forager returns to the colony, another worker takes the nectar from her honey crop and spreads the nectar over a wax honeycomb to evaporate it. (The nectar collected by foragers can be directly fed to brood and adults but is typically processed into honey first. Worker larvae consume 142 milligrams of honey during development.) Bees actively dry incipient honey out by fanning their wings over it.
Making honey is more than moisture control. Honeybees are adept chemists. At the onset of the honey production process, the nectar-harvesting bee adds a proper portion of invertase: an enzyme that breaks the sucrose in raw nectar down into the simpler, more digestible sugars dextrose and fructose.
After being processed, honey has only 18.6% water: so little that microbes cannot colonize it. The high osmotic pressure of honey, being ~80% sugar, is also inimical to microbes. A byproduct of invertase-provoked sugar breakdown is hydrogen peroxide, which is an antibacterial.
Some plants put antimicrobials in their nectar as an assist to their pollinators. More self-interested, but still helpful, are the antibiotics that plants tuck into their pollen.
Honeybees appreciate the antimicrobial property of their honey. ‘Nurse’ bees selectively feed medicinal honey, which is especially high in antimicrobials, to nestmates if they fall ill.
Dried honey is capped in the cell it was made in with an airtight wax seal.
Preserved in honey are the perfume, mineral salts, and nitrogenous products which the plants put in the nectar. This gives each honey a unique bouquet by its originating flower.
Honey consumption fuels wax secretion. It takes nearly 9 kg of honey for a young worker to produce 1 kg of wax.
Pollen
Unlike nectar, returning foragers pack collected pollen into cells on their own. Loose pellets are moistened with saliva and regurgitated honey, then packed into the bottom of cells by pushing the pellets with a forager’s mandibles. Packed pollen is often covered with a thin layer of honey as a preservative. Pollen stored this way lasts for many months, until needed. By tracking packing dates, bees rotationally consume their produce to avoid spoilage.
Wax
Honeybees and bumblebees make their nests of wax. Composed of esters (modified fatty acids), beeswax is derived from nectar. Workers craft wax by huddling together to raise their body temperatures, whereupon they secrete small wax flakes from glands in their abdomens. Ambient temperature must be 33–36 °C to secrete wax. The size of a bee’s wax gland size depends on its vitality; wax glands gradually atrophy. Once wax flakes have been excreted, other workers take them to the areas of the hive where they are needed to build cells for brood and the storage of honey and pollen.
Fresh wax is colorless and glass-clear, becoming opaque after mastication and intentional adulteration by workers. Beeswax becomes progressively yellower or browner by adding pollen oils and propolis, which bees know are anti-microbial.
Honeycomb
Honeybees are expert engineers. In making honeycomb, they literally use their head. Hair plates at the base of the neck serve as a plum bob to determine the line of gravity. Bees tilt the axis of the cells slightly up from the horizontal to preclude honey from flowing out.
Honeybees do not create the hexagonal shape that honeycombs take. Instead, they apply a little geometry and let physics do the work.
A regular geometric array of identical cells with simple polygonal cross-sections can take only one of 3 forms: triangular, square, or hexagonal. Of these, hexagons divide up the space using the smallest wall area. In honeycomb, hexagons use the least wax.
To form honeycomb, bees make cells that are circular in cross-section, packed together like a layer of bubbles. The wax, softened by bee body heat, gets pulled into hexagonal cells by surface tension at the junctions where the walls meet. 1 kg of wax can support 22 kg of honey: over 20 times its weight. Workers allocate wax with accuracy.
Honeycomb construction progresses seemingly randomly, since several bees contribute to building each cell and several cells are constructed simultaneously. Astoundingly, given the scattershot process, what results is precise: cell wall thickness is 0.073 ± 0.002 mm, the angle between adjacent cell walls is exactly 120°, and each comb is 0.95 cm from its neighbor. It is as if honeycomb is constructed via a singular mind.
There are usually 2 construction periods in a worker’s life: capping cells when young and constructing comb when older. Workers as young as 2–3 days can produce wax, though wax-producing glands are most developed at 8–17 days. Workers can work wax whether they secreted it or not.
Like many other chores, capping is commonly a somewhat unorganized process in which hundreds of workers each contribute a bit. A typical cell takes ~6 hours to cap, though an industrious worker may cap a cell by herself in only 20 minutes. However accomplished, every cap is properly and timely put on.
Comb construction is performed by older workers, albeit only a few days elder to brood-tending bees. A typical comb builder spends some of her time in a comb-building cluster, then goes off to work at various other tasks. Honeybees often have a lot of flexibility in their work schedules, subject to pressing hive needs.
Comb once built is a permanent part of the nest. Honeybees do not tear down cells and reuse the wax as other bees do. Instead, workers fastidiously clean cells after brood emerge or when stored honey or pollen is removed. (Cell diameters may diminish slightly over the years from material accumulation (cocoons, molting skins), even though cells are meticulously cleaned after every brood cycle. Workers reared in old cells may be a bit smaller.) Cells are repaired as needed. Cell caps are typically recycled.
The surface of honeycomb serves as a dance hall, meeting place, and scent depository (pheromones). A queen pipes vibratory broadcasts through the comb which are picked up by workers’ tarsi.
Guard Duty
10–15% of honeybees in a hive act as sentinels when they are 2–3 weeks old. Guards at the entrance have a characteristic posture: standing on their 4 hind legs with antennae held forward and forelegs lifted. Their main job is detecting and dealing with predators, but they are also the first point of contact when migrant honeybees arrive.
In an inspection that may last 30 seconds, guards inspect a newcomer for chemical cues that indicate relation to the home hive. If scented hydrocarbons reveal a suitable match genetically, the guards will let a drifter in. Once accepted into the nest, arrivals eventually blend in chemically: a visa evolves into citizenship.
Chemicals on bees’ body surface by which they are recognised as nestmates are acquired from the colony they are in. ~ English entomologist Francis Ratnieks
On average, ~30% of emigrant bees are allowed to stay. The admission rate depends upon the condition of the hive. When resources are abundant, such as nectar near the nest and fulsome honey in the combs, guards allow more newcomers in.
Conversely, an “open borders” policy can quickly change if food becomes scarce. Guards not only reject applicants but may even kill them. Combs lacking stored honey makes guards more aggressive.
Sentinels are also charged with apprehending marauding bees intent on stealing honey. These robber bees are detected by their flight patterns and speed. Approaching in a hurry will get an incoming bee stung before it even reaches the nest.
Guard duty for a worker is usually only a few hours before going off to another task. More workers guard the nest after a colony has been attacked or during times of scarce harvests, when robbing is more likely.
When flowers are wanting, desperate honeybees know that other hives may be their best shot at survival. A raid may last for days and leave hundreds dead.
If a marauding colony can overcome a hive, it will clean out all the honey and effectively eliminate the victimized nest. Once robbers have tasted victory, they may turn to other hives. Veteran marauders become smooth, shiny, and almost black – the occupational hazard of fighting other bees.
Foraging
Foraging is the most physically demanding job a honeybee can have. It is often the last job a worker has before she dies. 2 pairs of wings beat 200 cycles per second, flying near the limits of aerodynamics, in a wondrous ability to fly 2.4 kilometers per hour for up to 13 km at a crack.
Applying tremendous energy during flight, a forager must avoid overheating. She maintains her thorax (midsection) at 46 °C. She sheds heat from her head by regurgitating droplets of watery honey, thereby evaporatively cooling her head just as sweat does for mammals.
A forager averages 10–15 trips a day, but over 100 trips is possible: visiting up to 1,000 flowers per day. It is a grueling work regime. Many foragers last only 4–5 days.
Besides the food they eat, honeybees also produce their own antimicrobials. Foragers have an especially robust immune system which defends them against the pathogens they are likely to encounter outside.
Foraging activity is flexibly adjusted to meet colony needs. Further, foragers vary widely in their productivity: 20% of foragers amass 50% of the produce collected. A forager averages ~50% of her body weight in nectar, with the most productive bees maxing out at ~92%.
Hind legs carry pollen baskets (corbiculas) to be filled. Corbiculas carry pollen loads that average 20% of body mass. Pollen collectors may make more trips per day than nectar gatherers if pollen is available all day.
Other bee species are fonder of pollen than honeybees, who generally prefer harvesting nectar. The preference is somewhat individual: some honeybees prefer gathering pollen, others nectar. Most honeybees get some of both on their trips. Honeybees typically do what they like, albeit with hive needs in mind.
Honeybees commonly practice flower constancy: harvesting from the same flower species, either during a single trip or for days at a time. Flower constancy is efficient foraging, in readily having in mind a certain flower and how to quickly extract its bounty. Individual bees also tend to stick to foraging in the same areas, even as the same flower may be widely dispersed. This is also efficient in probabilistically knowing the most productive routes.
Most flowers are open for business only at specific hours of the day. Such an arrangement is advantageous to the plant because it increases the odds of suitable cross-pollination.
Flower-constant foragers learn the certain time of day that a flower secretes nectar or that a specific plant sap is available. These foragers tend to form a group that rest together in the hive when their chosen food source is unproductive. This makes sense because scouts or foragers can report specifically to interested cohorts current harvesting status.
Flower constancy group membership is fluid. As a certain flower wanes, bees move on to other kinds of flowers. A bee may simultaneously belong to 2 or more foraging groups, in which case she reports to the group which would be interested in what she has to say about her most recent trip.
All bees rely upon their sense of smell to locate new food sources. Honeybees possess especially keen olfaction.
Honeybees have sugar-detecting receptors (sensilla) in their mouth, and on their antennae and tarsi. A honeybee weighs the input from each sensilla in deciding whether to feed from a flower. The 1st input is given the greatest consideration. A bee can tell whether a flower is worth its time upon landing.
Tarsi can also sense saltiness. A bee hovering over a pond can detect its salt content.
1/4th of colony workers are foragers. Up to 1/3rd of foragers are scouts: on the lookout for new sources of pollen, nectar, tree resin, and water. Scouts tend to be more experienced foragers who prefer adventure.
Most foragers wait to be told what to do, but not scouts. Scouts go out and search for food on their own. ~ American entomologist Gene Robinson
Bees navigate by landmarks and distance. Not surprisingly, honeybees have excellent spatial acuity. Honeybees classify objects by color, symmetry (or lack thereof), and other characteristics.
A scout or forager that finds a rich food source returns to the hive and tells others how to get there by dancing directions. There are 2 forager dances: round and waggle. Both are based upon bees’ ability to see polarized light, which plays a vital role in bee navigation.
The Sun shifts 1° to the west every 4 minutes. The consistency of this change, coupled with bees’ circadian rhythm, lets them mentally maintain their bearings via innate, subconscious, algorithmic calculation, called Sun compass orientation.
A wealth of information is encoded in a honeybee dance, including direction, distance, and quality. Counted landmarks may also be conveyed.
If the food is within 100 meters from the hive, a round dance suffices: outline a circle in one direction on a vertical surface, then a circle the other way.
The more elaborate waggle dance gives detailed directions for faraway food: over 50 meters from the hive. If the source is in the same direction as the Sun, dance toward the top of the hive. Otherwise, adjust dance angle. (Dances typically occur on vertical surfaces.)
Dance speed and duration tells distance: slower means further. The pace is exact enough for onlookers to approximate distance. The waggle dance incorporates round dance elements. Geometrically, waggle dance patterns form a figure 8.
The enthusiasm a dancer expresses conveys the quality of the find. Passion promises a rich reward.
Foraging dances are not visual displays. The hive is dark. Dancing bees make distinctive vibratory sounds which are combined with emitted smells from a gland at the tip of the abdomen. These divergent sensory inputs are mysteriously transformed in bees’ minds into spatial maps. (Honeybees generally rely heavily on vibratory communication within their tenebrous nest.)
At the end of the dance, or when requested, a bee distributes harvested pollen or nectar to the workers paying her heed, so that they can sample the source. This later helps foragers identify the specific patch of flowers intended by the directions provided.
A scout’s solo dance may turn into dialogue – interrupted by a head-butt from another forager to warn that danger has been seen at the revealed location. The conversation may then turn into an interactive reward-risk analysis.
Predators are a frequent problem during foraging. Hornets launch aerial attacks. Spiders lurk on a flower and ambush a feeding bee.
Foragers leave scent marks on flowers where they are threatened by predator, warning others to stay away. Individual bees tend to be more risk-tolerant than colonies, where fear weighs more heavily in group decisions about foraging efforts.
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Bee dancing demonstrates that bees have an innate compass (abetted by brain-embedded magnetite), can tell time, and possess astonishing navigational and spatial memory. Bees also accurately gauge distance; well, mostly. Some subjectivity creeps in, which recipients may compensate for.
The tempo of the dances of a forager diminishes with age, so that she seems to indicate greater distances than when she was younger. ~ Charles Michener
The directions bee dances provide are the human equivalent of learning and memorizing geographical routes tens of kilometers away after being told a very few times (via sound and scent).
Besides foraging, the discourse of dancing is employed when assessing possible locations for moving the nest.
Scouts’ dancing directions are not the only honeybee jig. Younger receiver bees dance tremble dances, to recruit other receivers for harvesting sustenance from incoming foragers. The tremble dance can also act as a deterrent to foragers: an indication that food supply in the hive is abundant. Foraging dances, which lead to further supply, are curtailed. The effect is to reduce intake.
Symbolic honeybee dancing is an evolved adaptation, probably to conceal directions to prime foraging spots from illegitimate receivers. Stingless bees are known to eavesdrop on each other’s pheromone signals to foraging sites. Honeybee scouts may have taken their communications indoors to preclude such eavesdropping bees.
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The interaction between foragers and nectar receivers in the nest has a feedback effect. If the receiver likes what she is getting, she takes it quickly. If not, the forager may have to find alternate taker(s), as the initial receiver balks at offloading what she thinks is a pitiable harvest. If a forager cannot find recipients willing to take her crop, she must walk to a cell and regurgitate it herself.
The speed with which a forager can unload her nectar is a cue for her subsequent action. If the delivery time is short (and of course if the source is qualitatively and quantitatively suitable), she dances, sending other foragers to the same place, and soon returns herself. If the delivery time is long (over 60 seconds), there is little dancing, so few or no more bees are recruited to the food source. If the time is too long, the forager herself does not return but goes elsewhere or remains in the hive. This social interaction is an essential part of the control of the quality of the liquids brought into the hive. ~ Charles Michener
Young Again
In just 2 weeks, foragers have worn wings, hairless bodies, and are mentally fatigued. After 800 kilometers, a bee has worked itself to decrepitude.
A retired forager is thoroughly diminished. No longer able to effectively learn, her mind is largely spent. Aged bees that survive the foraging “experience” return to nest work.
When older honeybees take on nest responsibilities, typically handled by much younger bees, they need the mental acumen that the tasks demand. For this, bee brains are epigenetically enhanced. Aged brains are provided proteins that turn back the clock, allowing them the mental ability they need. Bodily reparation is not possible, but mind rejuvenation is.
Hive Maintenance
Honeybees live in a colony packed to a high density. A mature colony lives in a nest the size of a file box with 20,000 to 100,000 bees, depending upon the season. The winter represents a nadir in colony size. Colony population peaks in early June.
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A hygienic hive is essential to colony survival. 1% of all workers are constantly on sanitation duty of some sort.
Bee nests are immaculately maintained. Healthy adult honeybee workers never defecate in the nest. Sick and dead bees are quickly removed.
Worker bees constantly clean, including mutual grooming. The queen is kept clean by her court bees.
Resinous propolis is a multi-purpose cure-all for hive and health. For nest maintenance, propolis acts as a glue: used to close cracks, smooth rough edges, cement combs in place, and regulate the size of entrances, for security and temperature regulation. Bee glue applied to the hive also acts as an infection preventative.
If a colony does become infected with a harmful fungus or bacteria, workers produce extra propolis to take as medicine. As propolis has terpenes, which are antibiotic, it is often an effective treatment.
Plant resin is imbued with secondary metabolites expressly designed to protect a plant from infestation. With extensive botanical knowledge, bees selectively seek medicinal remedy from specific plants. They also choose to consume batches of honey high in the antimicrobial ingredients which may be most in effective in fighting an infection. Medicinal honey and propolis are distributed throughout the colony as needed.
Workers remove infected larvae from the hive. Grubs are too young to take propolis.
Honeybees can distinguish between harmful and harmless fungi. Harmless fungi worry them less: they do not self-medicate against fungi that do not present a health threat.
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Hive temperature is precisely maintained. The center of the nest – where the queen labors in egg-laying and young larvae are reared – is kept at 35 °C.
The whole hive throughout is kept within 2–3 degrees °C of normal, even though the temperature outside may range 10 °C. The active cooling system in a hive is a highly coordinated corps of fanners.
If the nest is too cool, bees distribute heat by absorbing it in their bodies, and then moving to a cooler area, where it dissipates. During winter, bees consume honey to generate internal heat, which they then dispense to warm the hive.
If a fungus happens to blight a hive, bees vibrate en masse to generate heat to thwart the threat. This is functionally the same as autonomic fever in endotherms to fight off an infection. The difference is that bees consciously know what to do when infected.
The brood area is naturally the warmest part of the nest, owing to the density of bees there, both adult and larvae. If the brood chamber gets too hot, nurse bees drop their crop about the brood cells to cool things down. Bee milk is ~60% water, so provides evaporative cooling. Then the nurses alert nectar receivers to have foragers bring water (or watery nectar) for distribution in the brood chamber. Fanners work to cool the brood down.
Water portage is a regular part of hive work, as honey is diluted in making brood food. Extra water is brought in for evaporative cooling of the nest as needed. Honeybees are constantly talking with each other about all kinds of things.
The first outside job a young bee has is wind generation: acting as an exhaust fan for the hive. Hundreds beat their wings 24,500 beats a minute to cool the colony and remove CO2.
Newly gathered nectar is generally so moisture-laden that it would ferment if immediately stored. Fanning removes excess moisture. Still, in the midst of a good summer harvest, a quarter of the nectar gathered the day before may be lost overnight.
Intelligence
Concepts are associated with high levels of cognitive sophistication. Concepts are well mastered by bees. ~ French zoologists Aurore Avargues-Weber & Martin Giurfa
Honeybees comprehend symbolic logic and employ it extensively. A honeybee handles concepts the same way that all minds do. Senses vary, but cognition via symbolism is universal.
Human decision-making strategies are strongly influenced by an awareness of certainty or uncertainty (a form of metacognition), to increase the chances of making a right choice. Humans seek more information and defer choosing when they realize they have insufficient information to make an accurate decision.
Honeybees selectively avoid difficult tasks they lack the information to solve. They assess the certainty of a predicted outcome. Bees’ performance was comparable to that of primates in a similar paradigm. ~ Australian zoologists Clint Perry & Andrew Barron
Hive members recognize one another by scent and sight, and by a vibratory sonic signature. Each bee’s exoskeleton exudes its own distinctive hydrocarbons.
Bees use vibrational signals for complex information. ~ German zoologist Taina Conrad
Honeybees have sophisticated multi-sensory languages involving gestures, scent, and sound. Beyond the foraging dances are many others, the meaning of which are often context-dependent, like much human oral communication. Likewise, there are many honeybee visible and tactile gestures. Besides a variety of sonic dances and other articulations, bees employ at least 18 pheromones to express themselves, which are often used in combination.
Pheromones exert considerable influence on honeybee behavior. ~ Mark Winston
Bee communication is articulate. For instance, bees can precisely describe dangers they have encountered.
A beehive is a constant communication network. Workers have many sources to learn of colony needs and adjust their behaviors accordingly. Bees socially learn, with older bees encouraging and instructing younger ones. This amounts to culture generationally passed down.
Honeybees do what needs to be done. Doing so is far from simple: running a honeybee hive is as complex as any human enterprise, and bees do better (though squabbles do happen from time to time).
Honeybees live in highly complex societies that show extreme forms of integration, cooperation, and communication. ~ Gene Robinson
Many tasks, such as cleaning brood cells, may be done by dozens of bees, with a single bee doing a bit of work on the task before moving to something else. This frees individuals from monotony at no expense of accomplishing everything that needs doing. Such casual coordination far exceeds what people can accomplish.
Foraging is an arduous but adventurous job. Some bees seem to revel in it. There are parallels to similar human endeavors, such as mountain-climbing, as well as simply enjoying being productive.
The collective mental harmony of honeybees is illustrated by their being caught in high winds while swarming. Swarming bees fly as a tight group. If buffeted by the wind, they responsively reform the shape to minimize the stress upon the swarm. This requires complex innate mathematical calculation as well as intricate group coordination. Some bees willingly suffer inordinate physical strain to accommodate the ideal formation.
Horizontally shaken clusters adapt by spreading out to form wider, flatter, more stable cones that recover their original shape when unstressed. ~ American mechanical engineer Oren Peleg
Collective dynamics allow superorganisms to function in ways that a single organism cannot, by virtue of their emergent size, shape, physiology and behaviour. ~ American evolutionary biologist J.M. Peters et al
Bees sleep and dream. Their need for sleep is like ours: to incorporate memories and stay mentally sharp. Honeybees sleep 5–8 hours a day. Having the most demanding job, foragers sleep longer than others.
Honeybee sleep patterns differ by age, and the company with which they slumber. Young bees are poor sleepers but show stronger sleep rhythms when spending the night with older bees. (Bee sleep rhythms reflect group energy, just as human group mediations are known to have a calming effect on conspecific life in the immediate vicinity.)
Honeybees are very smart. ~ German entomologist Hanna Zwaka
Bumblebees
Bumblebees are a larger cousin to honeybees. They too feed on nectar and collect pollen to feed their young. 250 species of bumblebee are known.
Bumblebees work harder than their honeyed cousins. They tirelessly toil in solitary for up to 15 hours each day: starting before dawn, and often finishing after the Sun has set. Large workers begin foraging at a younger age than smaller compatriots and are the most productive harvesters.
Like traveling salesmen, bees need to move between a large number of flower patches in the most efficient route possible. ~ English ethologist Joseph Woodgate
Bumblebees are astute in efficiently foraging. They learn through experience the most productive routes in their territory, effectively solving a perplexing mathematical problem.
Bees cannot inspect a map to find out where the best food sources are or plan how to get to them; instead, they must explore the landscape, discovering locations one by one, and then they face the challenge of integrating their spatial memories into an efficient route. ~ Joseph Woodgate
By examining petal color and other features that indicate profit potentiality, bumblebees can tell whether a flower is worthwhile before landing. A bumblebee can sense a flower’s fluctuating electric field, which tells it things we do not understand. Bumblebees also use cues from other bees, including honeybees, as to which flowers to avoid or spend harvesting time on.
Pollen is bees’ primary source of protein and lipids. Bumblebees choose a plant for the nutritional quality of its pollen.
~ American entomologist Anthony Vaudo
Though bumblebees often practice social learning, they make their own decisions. A bumblebee may decide that it knows better than the crowd where best to forage. Savvy bees do better than average.
Some species of honeybee and bumblebee leave a scent mark on a flower. Typically, until it degrades, the telltale scent deters visitation, as it marks a flower as temporarily tapped out. Conversely, a particularly rewarding flower may be scented to indicate its immediate fecundity.
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There is an old myth that bumblebees shouldn’t be able to fly, based upon a 1919 misunderstanding of aerodynamics. Theory at the time suggested that bumblebee wings were too small to create sufficient lift.
Bumblebee flight follows the aerodynamic principle employed for helicopters with reverse-pitch semi-rotary blades. Each oscillation cycle (back and forth) of a bee’s wings produces a temporary vacuum in the air above her, providing extra lift.
The fact remains that bumblebees have all the aerodynamic efficiency of the proverbial pig with wings. Nonetheless, bumblebees do have considerable maneuverability in the air. Their flight capabilities owe to brute power rather than design finesse.
Bumblebees have remarkable strength and endurance. Even after adding 20% more weight to its body with stored pollen, a bumblebee can fly as far as 6 km from the nest.
Although a bumblebee colony visits a wide variety of flowers during the blooming season, an individual bee practices mission-specific flower constancy, visiting only 1 flower species on a single trip away from the nest.
Most bees are proficient pollinators. A few have a superlative technique, buzz pollination: a bumblebee grabs a flower, then uses her body to create a powerful sonic vibration that shakes the flower, giving the bee a pollen shower.
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Compared to honeybees, bumblebees are rather docile. Nevertheless, if sufficiently provoked, a bumblebee has a barbless sting that can be repeatedly applied. Bee predators, including foxes, skunks, and shrikes, get an extra treat: a bumblebee sprays feces and vomits honey on them.
In contrast, other bee stings, such as the honeybee, are barbed. The sting cannot be removed without ripping the abdomen apart. Hence, a honeybee sting is the attack of a martyr.
Birds are bumblebee predators. Sometimes the tables turn. In temperate forests, birds and bees prefer tree cavities for comfy nests. Bumblebees particularly prefer a home insulated with plant materials. When a tiny bird, such as a tit, is finishing turning a tree hole into a home by laying in leaves and soft bits, a bumblebee may take over. Approaching the nest, the tit is warned off by the angry buzz of the bee. Unwilling to test its luck at close quarters against a serious stinger, the tit moves on.
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Bumblebees are gregarious, but nowhere near the elaborated eusociality of honeybees. Still, they teach their nestmates what they have learned. Bumblebee colonies may hold fewer than 50 individuals, although 400 is typical.
A bumblebee colony has a single queen. She is inseminated in the fall and hibernates through the winter. Bumblebee queens typically mate with a single drone, but polyandry is practiced in some species. Queens generally overwinter in a hole in the ground.
Come spring, a queen emerges to found a nest, typically constructed in an underground hollow, which she pads with grass blades. An abandoned mouse den will do.
The queen makes a small honey pot and lays 8–10 eggs inside it. Then she covers the pot with a wax canopy to prevent heat loss. Overnight, she sits on her brood like a hen, sipping from the honey pot. During the day, the queen collects more pollen and nectar to supply the pot.
The eggs hatch after 3 days. The queen cares for her offspring 16–25 days, until they mature.
The first workers a queen raises are often quite small. As the workers take over foraging and nest maintenance, the queen concentrates on egg-laying. The colony rapidly expands. The workers raised later are larger.
Bumblebee workers live 2 weeks; collecting nectar and pollen, making wax pots, and helping rear the next-generation eggs.
The queen’s last batch of eggs is of ~100 queens and ~100 drones, which hatch and fly to bring forth next year’s nests. At the end of the flower season, the queen dies, leaving her legacy.
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The life cycle of a bumblebee depends upon the length of the growing season. Bumblebees commonly live in higher latitudes and/or altitudes, though there are a few tropical species. Bumblebees near the Arctic Circle face a flowering season, and life expectancy, of 2 1/2 months. Some bumblebees in Central and South America have queens that can live 2 years, with colonies that reach a population of 2,000.
Stingless Bees
Meliponines – commonly called stingless bees – evolved on Gondwana ~100 MYA, long before honeybees first appeared. Like certain Australian solitary bees, meliponines independently evolved to fit niches occupied elsewhere by later-arriving honeybees and bumble bees.
Meliponines are native to tropical and subtropical biomes in Australia, Africa, Southeast Asia, and tropical America. Being tropical, meliponines are typically active year-round, though less so in cooler weather. Some species practice diapause (dormancy).
Meliponini females have residual, futile stingers; hence the designation of ‘stingless’. (The term stingless is something of a misnomer, as females in other bee tribes are incapable of stinging, as are all male bees. Further, meliponines do not lack stings: the stingers simply are so reduced as to be useless for defense.) These bees are not defenseless: they bite if disturbed.
Meliponines are eusocial, forming permanent colonies with a single queen, a corps of workers, and drones. Some meliponines have a soldier caste: defensive specialists like those found in ants and termites. Meliponini guards are larger than workers, and sometimes sport distinct coloration.
Meliponines typically nest in rock crevices, underground cavities, hollow tree trunks, or among tree branches. Like other bees, they build their own planned structures wherever they reside, using sophisticated construction techniques.
Like honeybees, meliponines have corbiculae (pollen baskets). Meliponines are usually generalist foragers. Scouts communicate to other workers about promising harvest fields, but do not dance as honeybees do.
Generally having smaller colonies than honeybees, meliponines produce less honey. Meliponini per-bee foraging productivity is often higher than honeybees. Meliponines store their honey within the nest in egg-shaped pots constructed of beeswax and propolis.
Meliponini honey is somewhat watery: 25–35% compared to honeybees’ 19%. To compensate, meliponines add more antimicrobials to their honey.
