We investigated egg-to-adult developmental time, adult longevity, adult body size, and wing and antenna length of Pimpla turionellae (L.) (Hymenoptera: Ichneumonidae) reared on Galleria mellonella L. (Lepidoptera: Pyralidae) last instars that were fed various doses of cypermethrin in diet. The impacts of cypermethrin on larval behavior, pupal weight, and last instar-to-adult developmental time of host species also were examined. Percentage of pupation at doses >20 ppm and pupal weight of G. mellonella decreased, whereas last instar-to-adult developmental time prolonged gradually with increasing doses of cypermethrin. Cypermethrin treatment increased the intensity of abnormal behavior and the number of host larvae on diet at 1, 2, 4, 6, and 24 h posttreatments at doses >50 ppm. The differences in egg to adult developmental time, adult body size, wing, and antenna length of P. turionellae were not significant. However, cypermethrin exposure significantly affected the adult longevity of female wasps. Mean longevity of cypermethrin-treated females increased significantly at all doses of insecticide tested with respect to controls except for 100 ppm. This work suggests that parasitoid species as well as its host are susceptible to cypermethrin in terms of remarkable adverse effects on biological characteristics possibly due to metabolic, hormonal, and nutritional deficiencies.