The workers of a typical honeybee (Apis mellifera) society are daughters of the same mother, all produced in a single season. In external morphology they are virtually indistinguishable. Yet at anyone time they differ markedly in their activities in the colony. Division of labour among nestmates-sometimes termed polyethism-is characteristic of insect societies. In honeybee colonies, its most basic features were recognized by Butler in 1609: that the morphologically distinct queen specializes in egg laying, and that there is an age-based division of labour among the workers, younger adults performing activities within the nest while their older sisters forage for food and water outside.