Reproductive aggression and nestmate recognition in a subsocial bee

► Discrimination among individuals is a prerequisite to many kinds of social behaviour. ► Ceratina calcarata is a subsocial small carpenter bee exhibiting nestmate recognition. ► Seasonal variation in aggression matches reproductive status. ► Reproductive females are more aggressive than nonreproductive females. ► Mothers are most aggressive to dwarf eldest daughters and coerce them into foraging.