Fascinating Facts About Worker Bees and Their Role in the Hive

Almost every honey bee you've seen on a flower was a female worker in the last weeks of her life. This is the story of everything she did before she got there.

Worker Bees’ Characteristics At A Glance

Three Kinds Of Bee, One Hive

A honey bee colony has three types of adult. Workers are easy to mistake for "just smaller queens," but the differences go well beyond size.

Here's the part that surprises people. A queen and a worker start from the exact same kind of egg. What decides her future is how she's fed. Larvae destined to be queens get royal jelly for their whole development. Worker larvae are switched after about three days to a diet that includes honey and pollen.

A strong colony in midsummer can hold 50,000 bees or more, and the overwhelming majority are workers. They are females that normally never reproduce. In summer, most of them are dead within six weeks.

From Egg To Adult In 21 Days

The queen lays a single egg at the bottom of a wax cell. For three days it stands upright, then slowly tips over and hatches into a legless, pearly white larva. Nurse bees feed it constantly. On about day nine, the nurses seal the cell with a wax cap. Inside, the larva spins a thin cocoon and turns into a pupa with all developed body parts. Around day 21, all the adults including worker bees, chew through the cap and climb out and get straight to work.

Worker Bee Anatomy

Worker bee has three body sections: the head handles sensing and feeding, the thorax handles movement, and the abdomen holds digestion, wax making and defense. What makes her special is how many of those parts have been adapted for jobs that a queen or drone never does.

Legs that work like a toolkit

Each pair of legs does something different. The front legs have a small notch lined with bristles, and she pulls her antennae through it to keep her sensors clean. The hind legs carry the famous pollen baskets, which are shallow dips ringed with stiff hairs. As she forages, she combs pollen off her body, wets it with a bit of nectar, and presses it into two neat pellets. A forager coming home with bright orange or yellow bundles on her legs has been doing exactly that.

Why the sting costs her life

The worker's stinger is covered in backward-pointing barbs. In the tough, elastic skin of a mammal, those barbs lock in place, and when she pulls away the stinger, venom sac and part of her abdomen tear off. She dies soon after. The detached venom sac keeps pumping for a little while, which is why beekeepers scrape a sting out quickly rather than pinching it. Against other insects, like a robber wasp, she can usually sting and pull free.

A built-in cargo tank

The honey stomach is a stretchy pouch that sits in front of her digestive stomach, separated by a valve. She can fill it with nectar or water, and a full load can weigh close to half her body weight. Then she flies it home. Try running with a backpack that heavy and you'll get a sense of why foragers wear out.

How a worker bee senses the world

She lives in two very different places: a pitch-dark, crowded hive, and a bright open landscape full of flowers. Her senses are tuned for both.

A Career That Changes With Age

This is the most relatable thing about worker bees. Nobody hands a young worker a job title. Instead, her body changes as she ages, and her work shifts with it. Glands for making baby food swell in her first couple of weeks, then shrink as her wax glands ramp up, and by the time she's around three weeks old, her body is ready for flying.

Different roles a worker bee has to serve throughout their lifetime are listed below:

• Days 1–2: Cell cleaner
  Cleaning and polishing empty cells. The queen won't lay in a cell that isn't spotless. Young bees also sit on brood to keep it warm.
  
• Days 3–11: Nurse
  Feeding larvae with secretions from her head glands. Some nurses join the queen's retinue, feeding and grooming her and spreading her scent.
• Days 12–17: Builder and storekeeper
  Producing wax flakes and shaping them into comb, taking nectar from foragers, packing pollen into cells, capping ripe honey, fanning, and removing dead bees
• Days 18–21: Guard
  Standing at the entrance and inspecting arrivals by smell. Bees from other colonies, and wasps, get turned away or attacked.

• Day 21 onward: Forager
  Flying out to gather nectar, pollen, water and propolis. Some become scouts that search for new food or, during swarming, a new home.

The Waggle Dance

When a forager finds a great patch of flowers, she comes home and tells her sisters where it is, using a dance on the vertical surface of the comb. Austrian scientist Karl von Frisch decoded this behavior, and it earned him a share of the Nobel Prize in 1973.

The sisters following her can't see the dance. They crowd around, touching her with their antennae and feeling the vibrations. They also taste and smell the nectar she brought back, so they know what kind of flower to look for. A forager who found something really good dances longer and with more energy, and recruits more followers.

Workers also have a few other signals. A forager who was attacked at a food source can head-butt a dancing sister while giving a short vibration, which works as a stop signal. And when too much nectar is arriving for the house bees to handle, foragers perform a "tremble dance" that gets more bees to switch over to unloading duty.

How Worker Bees Keep The Hive Running

Climate control

A steady temperature must be maintained in the hive for the optimum growth of all developing broods (at temperature about 34 to 35°C; 93 to 95°F). On cold days, "heater bees" disconnect their wings from their flight muscles and shiver those muscles, warming their thoraxes well above 40°C. Some heater bees press themselves against capped brood cells, or crawl into empty cells between them, to warm the babies directly. On scorching hot days, the job flips. Foragers bring home water and spread it in thin films, and rows of workers fan their wings to pull air through the hive, cooling it by evaporation.

Security

Every colony has its own smell, and guards check each incoming bee with their antennae. When a guard senses a threat, she can raise her abdomen and release an alarm pheromone that contains isoamyl acetate, a highly volatile compound which also gives bananas their smell. It tells nearby workers to get ready to fight. That's why beekeepers avoid bananas right before opening a hive.

Honey bees in Asia (Apis cerana) have an even more dramatic defense. When a giant hornet attacks a nest, these honey bees swarm it in a tight ball and vibrate their flight muscles until the temperature inside reaches around 46°C. The bees survive as they can tolerate heat up to 49°C while the hornet cooks.

Hygiene and medicine

A hive with tens of thousands of residents would be a disease disaster without constant cleaning. Undertaker bees carry dead sisters out and drop them away from the entrance, a process known as necrophoresis. Some workers can smell sick or dead larvae through the wax cap, open the cell and remove them, a trait called hygienic behavior. Workers also collect sticky resin from tree buds and turn it into propolis, which they use to seal cracks and coat the inside of the hive. It has antimicrobial properties, providing colonies "social immunity". Healthy bees, to prevent the spread of pathogens, don't defecate inside the hive either. In winter, they hold it in until a warm day allows a quick cleansing flight.

Group decisions

Workers make choices that shape the whole colony's future. If the queen dies, they pick a few young larvae and feed them with royal jelly to raise a replacement. When the colony gets crowded, they start building queen cells in preparation for swarming, where the old queen leaves with a large portion of the workers to found a new home.

Choosing that new home is a remarkable process. Scout bees fly out, inspect hollow trees and other cavities, and come back to dance (known as "waggle dance") for the best ones. Other scouts go check those sites independently and join the dance if they agree. Once enough scouts are dancing for the same spot, the swarm lifts off and flies there.

Workers also make one brutal decision needed for survival. Once the blooming season ends, food starts getting scarce and queen is no more laying eggs, they stop feeding the drones and drag them out of the hive.

Staying connected

Workers constantly share food mouth to mouth, a behavior called trophallaxis. Along with nectar, they also pass chemical signals through the colony, including the queen's pheromones. Those signals are part of how the workers get to know their queen is alive and laying. If she disappears, the colony becomes aggressive until they prepare a brand new queen.

Worker Honeybee Math

Based on the roles, worker bees are classified into forager bees and house bees:

Forager Bees: Honey starts as nectar, which is mostly water. A forager sucks it up, mixes in enzymes on the flight home, and passes it to a house bee.

House Bees: These bees add more enzymes and pass it along again. The nectar is spread into cells, and workers fan it until the water content drops to around 17 or 18 percent. Then they cap it with wax. What's left is honey, which stores almost indefinitely.

Summer Bees and Winter Bees

Here's a fact that even some beekeepers find surprising. Workers born in late summer and autumn are physically different from the ones born in spring. They have bigger fat bodies and higher levels of a protein called vitellogenin, which seems to help them resist aging. Because they rarely forage or raise large amounts of brood, they can live for months instead of weeks.

In winter, workers form a tight cluster around the queen. Bees on the outside act as an insulating layer, while bees in the core shiver to produce heat, and they slowly trade places so no one freezes. The cluster eats its way across the stored honey through the cold months, which is why beekeepers always need to leave enough behind.

Why Worker Bees Matter Outside Hive

When a forager moves from flower to flower, pollen sticks to her branched hairs and rubs off on the next bloom. That's pollination, and it's how many plants produce fruit and seeds. A widely cited 2007 study led by ecologist Alexandra-Maria Klein estimated that crops depending at least partly on animal pollinators account for about 35 percent of global food production by volume.

Honey bees aren't the only pollinators doing that work. Wild bees, flies, butterflies, beetles, bats and birds all play a part, and for some crops wild bees are actually more efficient. But honey bees are the ones farmers can truck in by the thousands of hives. California's almond orchards, for example, depend heavily on managed honey bee colonies brought in every spring. Apples, blueberries, cherries, melons and many other crops benefit too.

What's Making Her Job Harder

Beekeepers in many countries have reported high colony losses over the past two decades, and there isn't one single cause. The varroa mite is one of the biggest problems. It feeds on developing and adult bees, mainly on their fat body tissue, and spreads viruses like deformed wing virus. Pesticides are another concern.

The little we can do to help is to grow flowers that bloom at different times of year, ideally including local native plants. Avoid spraying pesticides on plants while they're flowering.  And buying honey from local beekeepers supports the people who manage colonies and monitor their health.

One last thought

The next time a honey bee lands on your sleeve, she's probably three or four weeks old. She has already cleaned cells, raised babies, built comb and stood guard, and now she's on the last and most difficult job of her short life. She has flowers to get to so that the future generations of her hive will easily survive.

FAQs

Q: Are all worker bees female?
A: Yes. Every worker honey bee is female. Drones are male bees while queen being a female don't collect food, build comb or defend the hive.

Q: How long does a worker bee live?
A: It varies. If born in spring or summer, about five to six weeks. However, workers born in late autumn, called winter bees, can live four to six months.

Q: Do worker bees sleep?
A: Yes. Honey bees have sleep-like rest periods, and experiments show that sleep-deprived foragers give less precise directions in their waggle dances.

Q: Can worker bees lay eggs?
A: They can, but their eggs are unfertilized and only produce drones. A healthy queen's pheromones mostly keep worker ovaries inactive, and other workers usually remove any eggs that workers lay. In a colony that stays queenless for a long time, "laying workers" can take over, and the colony slowly dies out because no new workers are born.

Q: Does a worker bee die after she stings?
A: If she stings a mammal, usually yes, because her barbed stinger stays stuck in the skin and tears away from her body. She can sting other insects without losing it.

Q: How much honey does one worker bee make?
A: Roughly one twelfth of a teaspoon over her entire life.

References

• Karl von Frisch, The Dance Language and Orientation of Bees (1967)
  https://books.google.com/books/about/The_Dance_Language_and_Orientation_of_Be.html?id=H3XMvgEACAAJ
• Thomas D. Seeley, Honeybee Democracy (2010)
  https://www.jstor.org/stable/j.ctt7t4bk
• Dyer, Neumeyer & Chittka, “Honeybee (Apis mellifera) vision can discriminate between and recognise images of human faces,” Journal of Experimental Biology (2005)
  https://doi.org/10.1242/jeb.01929  
• Klein et al., “Sleep deprivation impairs precision of waggle dance signaling in honey bees,” PNAS (2010)
  https://doi.org/10.1073/pnas.1009439108 
• Bateson et al., “Agitated Honeybees Exhibit Pessimistic Cognitive Biases,” Current Biology (2011)
  https://doi.org/10.1016/j.cub.2011.05.017
• Henry et al., “A Common Pesticide Decreases Foraging Success and Survival in Honey Bees,” Science (2012)
  https://doi.org/10.1126/science.1215039
• Mao, Schuler & Berenbaum, “A dietary phytochemical alters caste-associated gene expression in honey bees,” Science Advances (2015)
  https://doi.org/10.1126/sciadv.1500795
• Howard et al., “Numerical ordering of zero in honey bees,” Science (2018)
  https://doi.org/10.1126/science.aar4975