Abstract
Poets, philosophers and politicians have used bees, and often projected an idealized human society into their view of how beehives are organized, from the ancient Greeks to present times. We first review how division of labour in honeybees was perceived by human observers, before presenting our current understanding. We focus specifically on defensive behaviour and show that this model provides an interesting case study for our conceptual understanding of division of labour as a whole. We distinguish three phases of the defensive response: detection of an intruder, recruitment of individuals into collective defence and attack. Individual bees may selectively contribute to one or more of these steps. Guard bees monitor entering conspecifics or attacking mammals, and release an alarm pheromone to recruit stinging soldiers. However, we are still far from understanding why only subsets of bees become guards or soldiers (or even if soldiering can be considered a task per se). We discuss the stimuli associated with each of these steps, how they define the number of bees needed and how they might combine with individual and developmental characteristics such that individuals take on a particular task. We also highlight pending questions and interesting avenues for future research.This article is part of the theme issue 'Division of labour as key driver of social evolution'.