 Bumblebees are social insects which form colonies with a single queen . Colonies are smaller than those of honeybees , growing to as few as 50 individuals in a nest . Female bumblebees can sting repeatedly , but generally ignore humans and other animals . Cuckoo bumblebees do not make nests ; their queens aggressively invade the nests of other bumblebee species , kill the resident queens and then lay their own eggs which are cared for by the resident workers . 
