The queen bee explained

What she is

A queen is a female honey bee reared from an ordinary fertilised egg on a diet of royal jelly throughout her larval life. That diet, rather than any genetic difference, produces a larger bee with functional ovaries, a smooth unbarbed sting and a lifespan measured in years rather than weeks.

She emerges after 16 days, mates within her first two weeks, and then almost never leaves the hive again except to swarm. She lays up to two thousand eggs a day at peak — more than her own body weight daily — and can live three to five years, though commercial beekeeping usually replaces her sooner.

The mating flight

1. 1EmergenceShe chews out of her cell and, if there are rivals, seeks them out and kills them.
2. 2OrientationShort flights in her first days to learn the hive's position.
3. 3Mating flightsOver several days she flies to a drone congregation area — a specific aerial location used year after year — and mates with ten to twenty drones from other colonies.
4. 4ReturnShe stores several million sperm in her spermatheca and uses them for the rest of her life. She never mates again.

What she does not do

She does not give orders. She does not decide when to swarm, where to forage or how much brood to rear. She does not choose which cells to lay in — workers prepare the cells and she lays where they have prepared. She cannot feed herself for long and is fed by attendants.

What she does is lay and signal. Her mandibular pheromone spreads through the colony by contact and tells every bee that a laying queen is present. When that signal weakens — because she is failing, or because the colony has grown too large for it to circulate — the workers begin raising replacements. The queen does not decide this and cannot prevent it.

Supersedure, swarming and emergency queens

Emergency queens are the weakest of the three, because the larvae selected were fed worker diet for their first days. A colony that has raised an emergency queen frequently supersedes her within a season.

What happens without one

A queenless colony that cannot raise a replacement is on a clock. Within a few weeks some workers' ovaries develop and they begin laying — but they are unmated, so every egg is haploid and becomes a drone. A laying-worker colony fills its comb with drone brood in worker cells and dies out.

The exception is the Cape honey bee of South Africa, whose workers can produce female offspring from unfertilised eggs through a form of parthenogenesis. That ability makes it a serious pest when moved into African honey bee territory, where its workers can invade and take over colonies.

When a queen fails

Queen problems rank among the commonest concerns beekeepers report and among the commonest reasons given for colony loss. They take several forms: a virgin queen who never mates, a poorly mated queen who runs short of sperm and starts laying drones early, a queen who stops laying, and queens who simply disappear. Britain's National Bee Unit is blunt that no single cause explains poor queens. Known contributors include rearing queens from larvae that were too old and exposing queens to extremes of temperature in transport.

A queen who has run out of sperm can lay only unfertilised eggs, so the colony fills with drone brood in worker cells. Laying workers produce the same result in a colony that has lost its queen and has no young larvae left to raise a replacement, but their pattern is usually more scattered, often with several eggs to a cell. Telling them apart means finding the queen, or seeing how the eggs are laid; the inspection guide sets out what each sign can and cannot show.

Replacing a queen

A colony often replaces a failing queen by itself, through supersedure, and the result can be better than anything a beekeeper would have chosen. When beekeepers requeen, they are making one of three judgements: that the queen has failed, that the colony's temperament or health would improve with different stock, or that a younger queen will carry the colony further.

• Biology: an emergency queen is raised from a larva already fed as a worker for some days, and colonies frequently supersede one within a season.
• Principle: before replacing a queen for a poor brood pattern, rule out the colony's own problems — disease, mites, nutrition, pesticide residues — because a new queen in the same conditions may do no better.
• Principle: confirm that a colony is queenless before introducing a queen. A virgin queen is small, quick and lays nothing for a while, so a colony with one can look queenless.
• UK practice: the National Bee Unit suggests requeening queens older than two to three years after the summer harvest, because young queens keep laying later into autumn and are less likely to fail over winter. It is one authority's practice, not a rule about queens.

Where a new queen comes from matters too. Associations and breeding programmes often favour locally adapted stock, and genetic diversity within a colony has measurable benefits — the reason a queen mates so many times. But origin is not the whole story: in the north-eastern United States, how strong a colony was in autumn predicted whether it survived the winter better than where its stock came from.