Cohesion in social insect colonies is regulated by the use of chemical signals produced by the queen, workers and brood. In honey bees, signals from the queen are vital for the regulation of reproductive division of labour ensuring that the queen remains the only reproductive female in the colony. However, even with this strict level of control, workers can, in principle by her, activate their ovaries and lay eggs. In this talk, we focus on an example of exception to the rule in the workers of the African Cape honey bee Apis mellifera capensis Eschscholtz, where a single clonal lineage of this subspecies evolved into facultative parasites that actively seek out colonies of other honey bee subspecies, invade and take over the role of reproduction in the presence of the resident queen. We will present the behavioural and physiological traits that accompany this fascinating behaviour specifically how the parasites exerts reproductive dominance and how the host queens regulate them.