none Laboratory bioassays were conducted to determine the effect of insecticides on three species of tephritid fruit flies and associated parasitoids. First, topically applied malathion, carbaryl, and permethrin were tested against the Mediterranean fruit fly, Ceratitis capitata (Weidemann), the oriental fruit fly, Bactrocera dorsalis (Hendel), the melon fly, B. cucurbitae (Coquillett), and their corresponding parasitoids, Diachasmimorpha tryoni (Silvestri), D. longicaudata (Ashmead), and Psytallia fletcheri (Silvestri). Second, the effects of toxic baits on the three fruit fly species were tested by mixing insecticides with a protein hydrolysate bait. Insecticides used were malathion, naled, carbaryl, and permethrin. In a third test, we determined the effects of naled and malathion added to Staley's bait on C. capitata and D. longicaudata. Parasitoids were more susceptible to insecticides than the respective host fruit fly species. For example, D. longicaudata was 663 times more susceptible to permethrin than B. dorsalis, and D. tryoni was 680 times more susceptible to carbaryl than the C. capitata. Parasitoid response to insecticides varied by parasitoid species. The B. cucurbitae parasitoid, P. fletcheri, was less susceptible to these insecticides than the other two species. Topical and feeding tests showed that carbaryl was ineffective against fruit flies. Malathion was the most effective of the three materials tested topically against fruit flies. Naled was the most toxic insecticide in the protein bait tests. Staley's bait did not attract D. longicaudata, and this parasitoid was not as susceptible to malathion as C. capitata. However, D. longicaudata and C. capitata were equally susceptible to naIed. Application of these results to integrated pest management of fruit flies is discussed.