The mating strategies of male and female Ectropis oblique Prout were investigated with the aid of male antennae as an electroantennogram (EAG) detector and capillary-GC analysis. Each male was capable of mating with several females, but females that had received a spermatophore mated only once. Antennae dissected from males 0, 1, 2, 3, and 4 d post-mating and antennae from virgin males of corresponding ages displayed similar EAG responses to sex pheromone extracts from sexually active females. Pheromone extracts of mated females elicited significantly weaker male EAG responses than the pheromone extracts of virgin females. EAG responses of males to sex pheromone extracts taken from mated females at 0, 1, 2, 3, and 4 d post-mating were consistently weak. Pheromone production in the pheromone glands of mated females was strongly suppressed and declined during each of 4 successive nights after they had mated.