The grey flesh fly Parasarcophaga argyrostoma plays a role in human cutaneous wounds and eye myiasis as well as it acts as a parasitoid of various animals. The present study aimed to investigate the efficacy of methoprene on the adult performance and natality of this fly. Five dose levels (10.0, 5.0, 1.0, 0.1 and 0.01 μg/larva) of methoprene was topically applied onto the early last instar larvae and prepupae. The adult emergence of flies was completely blocked at the highest dose, regardless of the time of treatment. At other dose levels, the adult eclosion was partially blocked. Survival of the adult flies was adversely affected by the toxic potency of methoprene. Only at doses of 5.0 and 1.0 μg/larva, some morphologically deformed flies were observed. The total longevity of adult females was remarkably shortened in a dose-dependent course. Topical application of methoprene onto either last instar larvae or prepupae resulted in a considerably prolonged pre-larviposition period, but significantly shortened larviposition period. Topical treatment of either last instar larvae or prepupae with methoprene led to dramatic reduction in natality, in a dose-dependent course.