Honey Bees: Inside the Hive of One of Nature's Greatest Teams

What Makes a Honey Bee Special

There are more than 20,000 known species of bees, but only a small group are true honey bees. They belong to the genus Apis, part of Apidae, the largest family of bees. Scientists recognize only about ten living Apis species, and the genus most likely arose in South and Southeast Asia, where most of its species still live today.

Three features set honey bees apart from almost all other bees. First, they are eusocial: they live in large, permanent colonies with a division of labour so strict that a single bee cannot survive on its own for long. Second, they build long-lasting nests made of combs of six-sided wax cells. Third, they store surplus food as honey, which allows a colony to survive cold winters or dry seasons without flowers. That hoard of sweet, energy-rich food is exactly why honey bee nests are raided by so many animals, from bears and honey badgers to human honey hunters.

The best-known species is the western honey bee (Apis mellifera), originally native to Europe, Africa and western Asia and now kept by beekeepers on every continent except Antarctica. Its relatives include the eastern honey bee (Apis cerana) of Asia, the giant honey bee (Apis dorsata), which hangs enormous single combs from cliffs and tall trees, and the tiny dwarf honey bee (Apis florea), whose palm-sized comb is often built around a thin branch.

Life Inside the Colony

A healthy western honey bee colony in summer can contain tens of thousands of bees. Yet all of them belong to just three types, called castes, each with its own body and job.

The queen

Each colony normally has a single queen, the mother of almost every bee in the hive. She is longer than the workers, with a stretched abdomen built for egg-laying. At the peak of the season she can lay more than a thousand eggs a day. Despite her title, the queen does not give orders. Her main tools of influence are chemical: she releases a blend of scents called queen pheromone, which spreads through the colony as bees touch and feed one another. It tells the workers that a healthy queen is present and stops them from raising new queens. A queen can live for several years, far longer than any worker.

The workers

Workers are females, but they normally do not lay eggs. They do everything else: they clean, feed the young, build comb, guard the entrance, cool and heat the nest, and collect food and water. Remarkably, a worker changes jobs as she ages. Young workers stay inside, cleaning cells and feeding larvae. Middle-aged workers produce wax, build comb and process food. Only in the last stage of life does a worker become a forager, flying out to visit flowers. In summer this busy life lasts only about five to six weeks, while workers born in autumn can survive for several months to carry the colony through winter.

The drones

Drones are the males. They are larger and stockier than workers, with huge eyes that meet at the top of the head, helping them spot a queen in flight. Drones have no stinger, do not collect food and cannot even feed themselves well. Their only role is to mate with young queens from other colonies. When autumn comes and food becomes scarce, workers push the remaining drones out of the hive.

From Egg to Adult

Honey bees grow through complete metamorphosis: egg, larva, pupa and adult. Every bee starts as a tiny egg standing upright at the bottom of a wax cell. After about three days it hatches into a white, legless larva, which workers feed many times a day.

What a female larva eats decides her future. All young larvae first receive royal jelly, a protein-rich secretion made by glands in the heads of nurse bees. Larvae destined to be workers are soon switched to a diet that includes honey and pollen. A larva chosen to become a queen is raised in a special, larger cell and fed royal jelly throughout her development. The same egg can therefore become either a worker or a queen, depending only on food and care.

The sex of a bee is decided in another way. Fertilized eggs become females (workers or queens), while unfertilized eggs develop into males. This system is called haplodiploidy, and it means that drones have a mother but no father.

Development times differ between the castes. A queen needs about 16 days from egg to adult, a worker about 21 days and a drone about 24 days. Once a larva is fully grown, workers seal its cell with a wax cap, and inside it the bee transforms into a pupa and finally into an adult, which chews its way out.

A few days after emerging, a young queen leaves the hive on mating flights. High in the air, at places where drones from many colonies gather, she mates with a number of drones, who die soon after mating. She stores their sperm in a special organ and uses it for the rest of her life, never needing to mate again.

Wax and the Perfect Hexagon

Honey bees make their building material themselves. Workers of a certain age have four pairs of wax glands on the underside of the abdomen, which release small, thin flakes of wax. The bees chew and shape these flakes with their jaws and press them into place. Producing wax costs a lot of energy, and bees need to eat a large amount of honey to make it.

The comb consists of two layers of six-sided cells, back to back, hanging vertically. The same cells are used as cradles for growing bees and as jars for storing honey and pollen. The hexagon is no accident. Of the shapes that can cover a flat surface with no gaps, the hexagon encloses a given area with the shortest total wall length, so it saves wax. Mathematicians long suspected this, and in 1999 the American mathematician Thomas Hales published a proof of what is known as the honeycomb conjecture.

How Nectar Becomes Honey

Honey starts as nectar, a watery, sugary liquid produced by flowers to attract pollinators. A forager sucks up nectar with her long, tube-like tongue and carries it home in a special stomach called the honey stomach, or crop, which is separate from the stomach she uses to digest her own food.

Back at the hive, she passes the nectar mouth-to-mouth to younger house bees. During this process, bee enzymes, especially one called invertase, break down sucrose into two simpler sugars, glucose and fructose. The house bees then spread the liquid in thin layers inside the cells, and the colony fans it with their wings, creating air currents that evaporate much of the water. When the honey is thick enough, usually with less than a fifth of its weight in water, the bees seal the cell with a wax cap.

The result is a food that is very hard for microbes to spoil: it contains so much sugar and so little water that bacteria and moulds cannot grow, and it is also slightly acidic. Archaeologists have found honey in ancient Egyptian tombs that had survived for thousands of years.

Making honey takes enormous effort. A single worker produces only about a twelfth of a teaspoon of honey in her whole life, so every jar represents the work of a great many bees and countless visits to flowers. Bees also collect pollen, which provides protein and is carried home packed into small baskets on the hind legs, and propolis, a sticky mixture of plant resins used to seal gaps in the nest and to help keep germs in check.

The Waggle Dance: A Language of Movement

One of the most famous discoveries in animal behaviour is that honey bees can tell each other where food is. The Austrian scientist Karl von Frisch spent decades decoding this communication, and in 1973 he shared the Nobel Prize in Physiology or Medicine for his work on animal behaviour.

When a forager finds a rich patch of flowers far from the hive, she returns and performs the waggle dance on the vertical surface of the comb, in the darkness of the nest. She runs forward in a straight line while shaking her abdomen from side to side, then loops back around to the start and repeats the run, often many times.

• Direction: the angle of the waggle run compared with straight up on the comb shows the angle between the food and the direction of the sun. A run straight upward means "fly towards the sun"; a run pointing straight down means "fly away from the sun".
• Distance: the longer the waggle portion lasts, the farther away the food is.
• Quality: a forager that has found a particularly good source dances more energetically and repeats the dance more often, recruiting more nestmates.

For food close to the hive, bees use a simpler round dance, which tells others to search nearby. Followers also learn the scent of the flowers from the dancer's body. Bees even adjust for the movement of the sun across the sky during the day, an impressive feat for an insect with a brain smaller than a grain of rice.

Senses, Flight and Defence

Seeing the world differently

Honey bees have five eyes: two large compound eyes made of thousands of tiny units, and three small simple eyes, called ocelli, on top of the head. Bees cannot see red well, but they can see ultraviolet light, which is invisible to us. Many flowers have ultraviolet patterns, sometimes called nectar guides, that point bees towards the nectar. Bees can also detect the pattern of polarized light in the sky, which helps them find the direction of the sun even when it is hidden behind clouds.

The famous sting

Only females can sting, because the stinger is a modified egg-laying organ. A worker's stinger has backward-facing barbs. When she stings a mammal, the barbs catch in the elastic skin, and as the bee pulls away the stinger tears out of her body together with its venom sac, so she dies. When stinging other insects, however, she can usually pull it out again. The queen has a smoother stinger and uses it mainly against rival queens. A stinging bee also releases an alarm pheromone that smells a little like bananas and urges other guards to join the defence.

Heating and cooling the nest

Honey bees control the temperature of their home with surprising precision. The area where young bees are developing is kept at around 34 to 35 °C. On hot days workers fan their wings and spread water droplets to cool the hive by evaporation. In winter they form a tight cluster and shiver their flight muscles to produce heat, slowly eating stored honey for fuel. Unlike many insects, a honey bee colony does not hibernate; it stays active all winter.

Japanese honey bees, a type of eastern honey bee, use this heat as a weapon. When a giant hornet enters their nest, hundreds of bees surround it in a tight ball and vibrate their muscles, raising the temperature inside the ball to around 46 °C. The hornet cannot survive this heat, while the bees can.

Swarming: How Colonies Reproduce

A single bee is born in a hive, but a whole colony is "born" through swarming. In spring, when a colony grows crowded, the workers raise new queens. Before the first of them emerges, the old queen leaves with a large part of the workforce, often around half of the bees or more. The swarm settles temporarily on a branch or another surface, forming a hanging cluster, while the bees left behind in the old nest carry on with a new queen.

From the cluster, a few hundred experienced scout bees fly out to inspect possible new homes, such as hollow trees. Each scout reports her find with dances, and better sites attract more and more supporters. The American biologist Thomas Seeley, who studied this process for many years, showed that the swarm reaches a decision once enough scouts gather at one site, a kind of collective voting he described in his book Honeybee Democracy. Then the entire swarm takes off and flies to its chosen home.

Honey Bees and People

From honey hunting to beekeeping

Humans have sought honey since prehistoric times. A rock painting in the Cuevas de la Araña near Valencia in Spain, thought to be roughly 8,000 years old, shows a person climbing to collect honey from a wild nest while bees fly around. Some of the oldest honey ever found comes from Georgia: archaeologists discovered honey residues in clay vessels from a burial near Borjomi that is roughly 5,000 years old.

Ancient Egyptians kept bees in clay or mud pipes and showed beekeeping in temple reliefs more than 4,000 years ago. Honey was their main sweetener, and beeswax was used in medicine, art and mummification. At Tel Rehov in Israel, archaeologists found the remains of an apiary about 3,000 years old, with rows of clay hives.

The modern hive

For most of history, honey was harvested by breaking or destroying combs. That changed in 1851, when the American clergyman Lorenzo Langstroth designed a hive with movable wooden frames. His key insight was the bee space: a gap of just under a centimetre that bees leave open as a passage instead of filling it with comb or propolis. By leaving exactly this space around each frame, beekeepers could lift combs out, inspect the colony and harvest honey without harming the bees. Most modern hives are still based on his design.

Western honey bees were carried around the world by people. They are not native to the Americas, Australia or New Zealand, and were brought to North America by European colonists in the 17th century. In 1956, bees from Africa were brought to Brazil for breeding experiments, and some escaped. Their descendants, known as Africanized honey bees, spread through much of South and Central America and into the southern United States. They are known for defending their nests far more fiercely than European bees.

Pollination and the Threats Bees Face

Honey may be the most famous bee product, but the greatest gift of honey bees is pollination. As a forager moves from flower to flower, pollen grains stick to the branched hairs on her body and are carried to the next flower, allowing plants to make seeds and fruit. Honey bees are especially useful to farmers because colonies can be moved to where they are needed. Apples, cherries, blueberries, melons, sunflowers and many other crops benefit from their visits. California's almond orchards depend so heavily on honey bees that beekeepers truck hives there from across the United States every spring.

Honey bees are not the only pollinators, though. Bumblebees, solitary bees, flies, butterflies and other animals also pollinate crops and wild plants, and some plants are pollinated better by them than by honey bees.

Beekeepers in many countries have reported heavy colony losses in recent decades. Several problems often act together:

• The varroa mite (Varroa destructor), a parasite that originally lived on the eastern honey bee, jumped to the western honey bee and spread around most of the world. It feeds on bees and spreads viruses, and it is considered one of the biggest threats to beekeeping.
• Pesticides, including a group of insecticides called neonicotinoids, can harm bees' ability to navigate and forage. The European Union has restricted the outdoor use of several of them.
• Loss of flowers due to large single-crop fields, development and tidy, flower-poor landscapes leaves bees with less varied food.
• Diseases such as foulbrood, caused by bacteria, and infections by microscopic fungi of the genus Nosema weaken colonies.

In 2006, beekeepers in the United States began reporting a puzzling problem later named colony collapse disorder, in which most worker bees disappeared from apparently healthy hives, leaving the queen and food behind. Scientists have not traced it to a single cause, and it is now generally thought to result from a combination of stresses like those listed above.

Surprising Facts About Honey Bees

• A honey bee beats its wings around 200 times per second, which produces its familiar buzz.
• The honey badger's name comes from its taste for bee nests. In parts of Africa, a bird called the greater honeyguide leads people to wild bee nests and then feeds on the wax and larvae left behind.
• Bees use a special scent from a gland near the tip of the abdomen, called the Nasonov pheromone, to guide nestmates to the hive entrance or a new home. You can sometimes see workers standing at the entrance with their abdomens raised, fanning this scent into the air.
• Honey should never be given to babies younger than one year, because it can contain spores of bacteria that their immature digestive systems cannot yet handle.
• Beeswax has been used for thousands of years to make candles, seals, polishes and the moulds for casting bronze sculptures, and it is still used in cosmetics and food today.
• Workers keep the hive remarkably clean: they remove dead bees, and healthy bees avoid relieving themselves inside the nest, waiting instead for a flight outside.

From its dance language to its wax architecture and its role in feeding the world, the honey bee shows how far cooperation can take a tiny animal. Each worker lives only a few weeks, but together the colony behaves almost like a single organism that can live for years, plan for winter and choose its own home.