It has been proposed that in some queenless ponerine ants, includingOphthalmopone berthoudi, oviposition is triggered by mating, and that virgin workers are functionally sterile only because they are uninseminated. This mechanism would be unique amongst ants. By isolating newly eclosed virgin workers ofO. berthoudifrom mated workers, it was shown that they are in fact capable of laying eggs without mating. Virgin workers in intact colonies appear to be inhibited by a pheromone produced by their reproductively-active nestmates, as in other ants.