It took the nectar from five million flowers to make the pint of honey setting on your kitchen shelf. Thousands of honeybees each visited hundreds of flowers a day, working from sunup to sundown. And, at only about 30 days of age they died, simply worn out. We may tend to think of the value of honeybees as limited to that deliciously sweet topping, but, they give us so much more: They’re the most important pollinators of fruits and vegetables. In the U.S. alone honeybees are responsible for 80 percent of flowering crops and $18 billion a year in commerce. If not for honeybees, we’d probably never again eat an almond, apple, melon, strawberry or, of course, honey. What your salad bar would look like without bees.
How bees help pollinate
Bees have a fuzzy body that carries an electrostatic charge which causes pollen (male plant parts) to loosely stick to it. Some of the pollen is brushed off onto female plant parts as the bees move from flower to flower. So simple, yet so important.
Bees are in the order Hymenoptera (HY-men-OP-ter-uh), which is from Ancient Greek hymen + pteron, literally meaning “membrane wings.” Hymenoptera also includes wasps, ants, and sawflies. Bees evolved from a wasp-like ancestor and have been around since the middle of the Cretaceous Period, about 120 to 130 million years ago. Scientists think bees and flowering plants may have evolved together.
There are about 20,000 bee species in the world. The smallest are Australian species in the genus Quasihesma, only 0.08 inches long (2 mm). The world’s largest bee is an Indonesian species called Wallace’s Giant Bee, Megachile pluto; the female can grow to 1-1/2 inches long (39 mm). Bees are found on every continent, except Antarctica, wherever nectar-producing plants grow. There are seven species and 44 subspecies of honeybees, all in the genus Apis.
Within each species, the queen bee — the only bee that lays eggs — is always the largest in a nest. Her abdomen is more pointed and her stinger lacks a barb at the tip. Females (workers) are the smallest in the nest. Males (drones) fit in the middle.
Bees have three body sections — head, thorax and abdomen. Much of the body is covered by an external skeleton (exoskeleton), rather than an internal one. The exoskeleton is made up of hard, moveable plates of chitin (other animals with chitinous exoskeletons include crabs and lobsters). There’s also a lot of fuzzy hair on their body, which collects pollen and helps regulate body temperature.
The head contains the brain, which is made up of neurons that communicate with neighboring neurons that together can perform complex tasks. Nerves connect the brain to the rest of the body.
On the head are two antennae, two large compound eyes and three simple eyes. Each compound eye is made up of about 150 small eye parts called commatidia, which specialize in seeing patterns and colors in ultraviolet (UV) light.
The bee’s mouthparts are complex and consist of a pair of mandibles (jaws), a tongue (gloss), and a labrum and two maxillae, which are like lips and support a proboscis (pro-BOSS-kiss), which is tube-shaped for sipping nectar. Males lack the necessary mouthparts to gather pollen and nectar from flowers.
The second body section is the thorax. Two pairs of wings and three pairs of legs are connected to it. The legs are basically like that of other insects, having a coxa, trochanter, femur, tibia and tarsus. Each hind leg has a polished cavity surrounded by hairs — called a pollen basket, it collects pollen as the bee moves around on flowers.
Bzzzzzz! That sound we hear when bees are near is caused by the speed of their wing beats — 280 beats per second!1 Yet, they’re extremely thin and fragile. A row of hooklets called hamuli (HAM-u-lie; sing: hamulus) on the back wings attach to a fold on the edge of the front wings; this causes them to beat together in flight, appearing as though they have only one pair of wings.
The abdomen doesn’t have anything noticeable attached to it — well, there is that one thing that can send grown people fleeing in terror! The stinger! Female bees have one, males do not. It’s used as a weapon only when necessary. The sting (also called stinger) is a female’s egg depositor (ovipositor), but it’s attached to a sac of venom that gets injected if she’s forced to stab something with it in self-defense. She doesn’t use it indiscriminately — to sting means certain death. That’s because the stinger’s tip is barbed and gets stuck in the victim. so, when the bee stings and flies away, the stinger gets pulled out of her abdomen, wounding her fatally. (Females of most bee species have stingers, but there are a few species that don’t. Many other species, including bumblebees, lack a barbed tip and can sting repeatedly.)
Senses and intelligence
In 1919 Australian zoologist Karl von Frisch discovered through a series of tests that honeybees have color vision. Also, that they can be taught to discriminate between two divergent paths leading to food by following the correct color markings. Not only that, but they retain memory of the learned color. Except for red, honeybees can see all the colors we do, but they have trouble distinguishing between them. They also see ultraviolet light. We don’t really know what color UV light actually is, because humans can’t see it, but scientists call it “bee purple.” The importance of UV light for bees is that it uncovers colors and patterns which draw them to nectar sources. The photo shown here compares visual light and UV light. We can’t know what color a bee actually sees in UV light, but we can see how the patterns in the flower stand out. Recent research (2018) indicates that honeybees understand that zero is less than one, meaning they understand the concept of “nothing.” It takes children several years to learn this.
Honeybees “hear” by detecting the movements of air particles. They can hear a dancing bee from several millimeters away. (By contrast, sound waves also can be heard in another way, through the detection of pressure oscillations, which is how humans hear. ) A sense of taste is vital for the bees. They taste foods, resins, water and members of their colony. Their taste sensors are located in hairs on the last segment of their antennae, on their mouthparts and on the feet of their forelegs. They can distinguish between sweet, sour, bitter and salt. They also have a sense of touch. They use their antennae to gauge width and depth when constructing cells in their honeycomb. They also communicate through touch during bee dances.
Honeybees also have a sense of touch. They use their antennae to gauge width and depth when constructing cells in their honeycomb. They also communicate through touch during bee dances
Bee stings and our body’s response
Bee venom contains peptides and enzymes that destroy fats that line cells, as well as immune system cells in the skin. When a person is stung, their body releases histamine, which causes blood vessels to dilate so that other immune cells can reach the injection site as fast as possible to neutralize the venom. For most people, a bee sting causes localized sharp burning pain, a red welt, a small white spot where the stinger punctured the skin, and slight swelling. The reaction goes away in a few hours. Some unfortunate people are allergic to bee stings and their body releases too much histamine. The blood vessel dilation is extreme and leads to a cascade of life-threatening reactions — as blood pressure drops, cells stop receiving oxygen, swelling and spasms ensue. Without intervention, this can lead to death. An injection of epinephrine, which constricts blood vessels, usually halts the process.
Honeybees are social bees, called so because they live in large groups. They use waxy secretions to build nests and cells within it for raising young. Bumblebees and stingless bees (native to tropical regions) are solitary, except to mate, and the females build their own nest. They do it in different ways and places, depending on the species. For example, carpenter bees bore holes in unfinished wood, while plasterer bees dig holes and tunnels. Nests are built in convenient places, such as abandoned wasp nests, empty snail shells and in tree cavities, or in the ground. The females lay their eggs in the nest, fill it with pollen and nectar for hatched offspring to feed on, and then leave.
A social bee begins a hive (or colony) when a single queen (there’s never more than one) uses wax from her wax glands (located in the lower part of her abdomen) to construct cells in which to lay eggs. She alone tends to her first offspring. From then on, the queen’s sole role is to lay eggs, while her offspring, almost all of them female, take over all duties and the care of young.
Over time, a hive may become overcrowded and needs to be divided, so the colony starts a new queen by raising a bee on a food called royal jelly. Royal jelly is water containing protein, sugars, fatty acids, trace amounts of minerals and vitamins, and an antibiotic component. It’s produced by glands within the hypopharnyx (located in the head) of worker bees. (Royal jelly is sold in health food stores for its antioxidant, anti-inflammatory and other health benefits.) A single protein called royalactin seems to be responsible for developing a bee larva into a queen. The old queen leaves the hive, taking with her about half her colony, and the new queen will fill her vacancy.
Each bee has a role to play…or many
The queen bee is the only female bee in a hive with mature reproductive organs. She can be identified because she’s always the largest bee in a hive, much larger than the others, and her wings are shorter. Also, she lacks pollen baskets. Her sole role is to lay eggs for the duration of her life, which is two to five years. She is capable of grooming and feeding herself, but is usually tended to by worker bees, especially after she has mated and is carrying eggs.
Worker bees are the smallest bees. They have a shorter abdomen and pollen baskets on their hind legs. They’re always females, but lack developed ovaries and can’t lay eggs. Working as a team, they perform all the work in the colony. Their duties include feeding and caring for larvae and the queen, building the honeycomb, removing dead bees, waste and debris from the hive, collecting nectar, pollen, resins and water, producing beeswax and defending the hive. Their tasks change as they age and upon the needs of the hive. Depending upon the age of a hive and the time of year, it may contain 20,000 to 60,000 workers. They live only a few weeks through the warm seasons, having pretty much worked themselves to death. Those born in late summer will live through the winter.
“Drones” are the male bees. Larger than worker bees, they have stout bodies and their eyes are bigger than those of the queen and workers. Their sole purpose is to mate with queens.
Honeybees develop through a process called complete metamorphosis. They begin as eggs, hatch as larvae, then pupate, then emerge as fully grown adults. Each stage looks different from the one before.
Courtship begins at a mating site where males have gathered to await females. It isn’t known how males make a decision about where to meet. Queens travel some distance from their colony to mate, which helps to avoid inbreeding, and they mate with several males. Mating occurs in midair, with the female collecting as much sperm as she’ll need for her entire life.
The life of male is short — he’ll probably die right after mating, because his sex organ (endophallus) is pulled from his body as he flies away from the queen. “Unlucky” males, meaning those that failed to mate, are actually lucky for a time, at least from a human standpoint. With bodies still intact, they might stay in their hives through spring and summer, feeding from the nectar there and often tended to by the workers. But, they eat about three times as much as workers and when nectar sources become scarce in the fall, their luck runs it course as worker bees drive them away. Male bees are capable of feeding themselves, but they don’t collect nectar or pollen from flowers, so outside the hive they starve to death.
After mating, the queen lays a single egg in each cell in the brood area of her hive. She controls whether to use some of the sperm stored in her body to fertilize an egg as it passes through her vagina, which then develops into a female bee, or leave the egg unfertilized, where it becomes a male. Workers play a role in “informing” the queen as to when and to what degree her services are needed.
Sources vary as to how many eggs a queen lays. The number is somewhere between 1,000 and 3,000 eggs a day and up to a million eggs in her lifetime. One thousand or 3,000, it’s an impressive number! (There are more restful periods of time when the queen lays no eggs or fewer eggs, such as in the winter.) It’s estimated that workers make 110,000 visits to each egg during its egg and larval stages.
Larvae resemble pearly-white, shiny grubs. At first, they’re curled in the shape of a “C” at the bottom of their cell. As they grow they stretch out length-wise and eventually fill their cell, molting (shedding skin) several times as they outgrow their skin.
Eggs hatch in three days. The youngest workers take care of the larvae, feeding them royal jelly for the first two days. After that, they feed them pollen or “bee bread,” a mixture of pollen and nectar. After 9 or 10 days, workers cap the brood cells with beeswax. Closed within their cells, larvae spin cocoons for themselves from silk glands located in their mouthparts and begin to pupate. Full development time from egg to adult varies according to a bee’s caste. It takes queens about 16 days, workers 21 days and drones 24 days.
An exception to the feeding regimen is made when raising new queens: Several female larvae, apparently picked at random, are fed only royal jelly, which causes them to develop differently from the other female larvae. After emerging as adults, new queens fight to the death, until only one remains. They’re able to sting their competition repeatedly, as their stingers lack a barb.
Workers determine a new queen is needed when their existing queen begins to fail or slow down with age; goes missing from the hive for some reason; or flies off with part of her colony to form a new colony (called swarming).
Swarming is the way new honeybee colonies are created. It usually occurs in the spring and when a queen is about two years old. Rarely there will be successive swarms for some reason that nearly empty a hive.
A queen swarms from her hive, taking with her about 50 to 60 percent of her worker bees, to start a new hive. That can mean 25,000 to 30,000 bees flying en masse! Before this happens, the workers and queen do some preparation: The queen lays a few eggs to leave behind for workers ) to raise as new queens. After that, she stops laying eggs. Workers stop feeding her to decrease her weight, as she’ll have to fly a long distance with a body heavy with sperm. Scout bees, the most experienced foragers in the colony, are sent out to find a suitable intermediate stopping point (often only a few yards away, on a tree trunk or branch).
Before the new queens emerge from pupation, the old queen and her followers leave the hive for good. They fly to the intermediate place and cluster together. Several dozen of the most experienced scouts go forth in search of a suitable new hive location. Usually this is only a short wait, a few hours. Without a newfound source of nectar, they’ll starve to death in about three days. They face other risks, too: They’re outside in full view of predators, the queen may be attacked and die, or the weather could turn bad, causing the destruction of the entire colony.
The scouts will return with their recommendations, based on sufficient size, availability of nectar, protection from the elements, warmth, protection from other insects, and perhaps other factors. Each scout conveys the distance and direction to her site, usually a cavity of some sort, with a variant of their “waggle” dance; the keener she is about her find, the more excitedly she dances. The scouts “discuss” in this manner until they reach a consensus, and the cluster follows them to their new home site. (Unsurprisingly, beekeepers have methods they use to try to reduce swarming.)
The “tremble” dance: A worker moves about the hive while quivering her legs. This dance communicates that so much nectar has been brought to the hive that foragers need to stop gathering for a time and help process it. The “round” dance: A forager arrives at the “dance floor” (located near the entrance) and runs around in narrow circles and then quickly reverses direction. This indicates that food is close to the hive, but doesn’t convey the direction.
The “waggle” dance: A forager arrives at the dance floor and performs a figure-eight pattern while fluttering her wings and shaking her abdomen. Her movements convey direction and distance from the hive and richness of the source. How? Her body in relation to the sun shows the direction. The length of time she performs the dance (in milliseconds) conveys distance. The vigor of her dance indicates the richness of the source.
The “shake” dance: A forager moves throughout the hive and shakes her abdomen in front of non-foragers to signal them to move to the dance floor. This is performed by a forager when the nectar source she has found is particularly good and more foragers are needed. The “sickle” dance: A crescent-shaped dance conveys that food is located 50 to 150 meters from the hive, but doesn’t communicate direction.
Bees feed on nectar and pollen. Nectar is a liquid that’s rich in sugar and provides them energy. Pollen is a coarse powder that’s protein-rich and contains male sperm cells. While moving around plants, the hairs on a bee’s body both trap and release pollen. The pollen fertilizes the female plant parts it touches.
Foraging worker bees travel in a 2 to 3 mile radius in search of food. They bring pollen back to the hive, which has been collected in their pollen baskets. To keep it from blowing away when their flying, they mix it with nectar and salivary secretions, which hold it securely. The composition of pollen varies depending on the plants it’s collected from. Back at the hive, the pollen is passed to other workers who use their heads to pack it into cells.
Predators and defenses
Honeybees face many predators as they go about their busy lives. Bears love to raid beehives to steal honey. Bees fall prey to carnivorous insects waiting to ambush them as they collect nectar and pollen. Bees get caught in spider webs. Predators also include small mammals, reptiles, amphibians and birds.
Honeybees defend themselves by flying away from predators or stinging them. They don’t sting unless necessary. Their stingers have a barbed tip, which remains stuck in the predator’s body when the bee flies away, mortally injuring the bee. A group of bees stinging a predator may drive it away, or even kill it. Bees marshal their forces when their hive is attacked. At least one study suggests they have different attack strategies depending on the kind of predator.4
Queens live two to five years. Females live only a few weeks, except those born in late summer who live through the winter in their hive. Most males die soon after mating. Some males who didn’t mate stay in their hives through the summer. Females drive them out in the fall and they die starve to death.
¹ Source: California Institute of Technology, which has conducted research on bee flight
² A few researchers believe that dances are performed only to attract attention so that “odor plume” information can be conveyed, which leads bees to nectar.
³ In 1973, along with Nikolaas Tinbergen and Konrad Lorenz, Karl von Frische received the Nobel Prize for his work in animal social behavior.
4″Self-organized defensive behavior in honeybees,” PMC/PNAS
*Top photo: European Honeybee, Apis mellifera. (Eran Finkle / Flickr; cc by 2.0)