A bee's jobs change with age

A worker does not keep one job for life. As she gets older, her tasks change in a typical order, a pattern called age polyethism (age-linked division of labour). In a summer colony a worker lives about six weeks, and her life looks roughly like this:

The ages are typical values and overlap. Notice that the most dangerous jobs come last: the bee spends the first three weeks of her adult life inside, and only then flies out, where predators, bad weather and long flights wear her out in a matter of weeks.

Timetables are flexible. The schedule above is an average, not a rule written into each bee. The colony adjusts it to what it needs:

• If many foragers are lost to a storm, some younger bees start foraging early.
• If almost all the young bees are missing, some older foragers can go back to nursing, and their glands can work again.
• If a lot of brood needs feeding, more bees stay on as nurses for longer.

Biologists have found that a bee's chemical signals and the state of the colony (for example how much brood there is, and how much food has been collected) influence how fast she moves from one job to the next. In World 6 we will see a simple model of how such flexibility can arise without a boss.

A worker's working life, in numbers. If she emerges on day 0 and becomes a forager on day 21, and lives about 42 days in all, she spends about 21 days inside and about 3 weeks outdoors. That means roughly half of her life is spent in work inside the hive, before she ever leaves it.