Anarchistic honeybees result from extremely rare behavioural mutations which allow workers to lay eggs despite the presence of the queen. We investigated the behavioural development of bees derived from a line in which ca. 5% of workers have developed ovaries and lay viable eggs. Other than their developed ovaries and proclivity to lay eggs, the anarchistic workers we studied are apparently normal, performing normal worker–like behaviour. Unlike many laying workers in queenless colonies, they are not queen–like and are apparently not the objects of aggression. When day–old workers from anarchistic colonies were cross–fostered into anarchistic and wild–type host colonies, the frequency of ovary development was an order of magnitude higher in the anarchistic host (9.1%) than in the wild–type host (0.7%). This suggests that there is a policing mechanism that affects ovary development in honeybees. Thus, worker reproduction is probably suppressed at the level of ovary development as well as by oophagy of worker–laid eggs. Other mechanisms, such as aggression towards individuals with developed ovaries, may also exist, but we found no evidence for this.