We measured the acceptance and suitability of four aphid species (Aphis gossypii Glover, Myzus persicae (Sulzer), Rhopalosiphum padi (L.), and Schizaphis graminum (Rondani)) (Homoptera: Aphididae) for the parasitoid Aphidius colemani Viereck (Hymenoptera: Braconidae). Female parasitoids parasitized fewer R. padi than the other three aphid species, and fewer offspring successfully completed development in R. padi than in the other three host species. Sex ratios of emerging adults were more male-biased from R. padi than from the other three aphid species, suggesting that R. padi is a poor quality host for this population of A. colemani. Ovipositing A. colemani encountered R. padi at a slower rate, spent more time handling R. padi, and parasitoid offspring died at a higher rate in R. padi compared to A. gossypii. Our results show that oviposition behavior and offspring performance are correlated. In each experiment, we tested the effect of the host species in which the parasitoids developed (parental host) on the number of hosts attacked, the proportion of each host species accepted for oviposition and the survival of progeny. Parental host affected maternal body size and, through its effect on body size, the rate of encounter with hosts. Other than this, parental host species did not affect parasitism. Aphidius colemani (Aphidiidae) : Parasite Aphis gossypii (Aphidoidea) : Host Myzus persicae (Aphidoidea) : Host Rhopalosiphum padi (Aphidoidea) : Host Schizaphis graminum (Aphidoidea) : Host Reproduction; Reproductive behaviour; Life cycle and development; Evolution; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Ecology; Population dynamics; Population structure Aphidius colemani; Egg laying; Oviposition; Development; Natural selection; Hemipteran hosts; Host species use evaluation; Aphidoidea; Population sex ratio Aphis gossypii; Myzus persicae; Rhopalosiphum padi; Schizaphis graminum; Hymenopteran parasites; Host species use evaluation; Aphidius colemani none