Bracon hebetor (Say) (Hymenoptera : Braconidae) is a gregarious parasitoid that attacks a variety of important lepidopterous pests of stored product and in the field. In this study the effect of host species, size and larval competition on parasitoid size, survival and development were investigated. In laboratory studies, wasp eggs at a range of densities, were placed on larvae of different weight of three Lepidoptera host species namely Adoxophyes orana (Fischer von Roslerstamm, Tortricidae), Plodia interpunctella (Hubner, Pyralidae) and, Lobesia botrana(Dennis & Schiffermueller, Tortricidae). On A. orana survival of immature parasitoids was very low at all densities and different host weights. On L. botrana survival progressively reduced as egg density increased at both host weights examined for this host. Survival on P. interpunctella was significantly affected by egg density but not by host weight. Initial egg density had a significant effect on the size of emerging adults from each rearing host. Smaller adult parasitoids emerged as egg density per larva increased. Larval host weight of P. interpunctella and A. orana had a significant effect on the size of emerging adult parasitoids mainly at the higher egg densities used in these experiments. The above results of host quality on fitness of parasitoid are discussed. Plodia interpunctella (Pyralidae) : Host Adoxophyes orana (Tortricidae) : Host Lobesia botrana (Tortricidae) : Host Bracon hebetor (Braconidae) : Parasite Biometrics; Reproduction; Reproductive productivity; Life cycle and development; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Ecology; Population dynamics; Competition Adoxophyes orana; Lobesia botrana; Plodia interpunctella; Weight; Hymenopteran parasites; Host species; size & parasite larval competition effects on parasite size; survival & development; Bracon hebetor Bracon hebetor; Weight; Egg number; Development; Lepidopteran hosts; Host species; size & parasite larval competition effects on parasite size; survival & development; Adoxophyes, Lobesia & Plodia; Survival; Intraspecific competition none