Because of different defence mechanisms - for example, cleaning activity and the high susceptibility of the worker brood - varroa mites can only reproduce in Apis cerana in the drone brood, and only in limited numbers. Consequently, mite control in the colonies is not necessary with this honey bee species. Occasionally, hives of Apis mellifera also survive infestation with this parasite, even without treatment. We are studying several of these populations in order better to understand their capacity for resistance. The information gleaned from our study could be used to breed honey bees that are resistant to this parasite.