In this research, the effects of profenofos, thiodicarb, hexaflumuron and spinosad were studied on functional response of Habrobracon hebetor to different densities of last instar larvae of Anagasta kuehniella. Two day-old mated females were exposed to LC25 of the insecticides and distilled water as control. Host densities of 2, 4, 8, 16, 32 and 64 were offered to treated females wasps for 24 h in 10 cm petri dishes. Experiments were conducted in 8 replications and were carried out in controlled conditions, 26[plus or minus] 2[degree]C, 70[plus or minus] 5% RH and 16:8 (L:D) h. The type of functional response was determined using logistic regression and the parameters, searching efficiency (a) and handling time (Th) were estimated by non-linear regression using SAS software. Functional response was type II in control and all of insecticide treatments. Searching efficiency in control and insecticide treatments were 0.0935, 0.0132, 0.0511, 0.0864 and 0.0905 h-1 and handling! times were 0.4542, 1.0646, 0.5381, 0.5275 and 0.4896 h, respectively. The maximum attach rates (24/Th) were estimated 22, 52, 44, 45 and 49, respectively. Spinosad and hexaflumuron had the most and the lowest effect on searching efficiency of H. hebetor, respectively. BR Parasites diseases and disorders. Parasites. Insect parasites. Hosts. Insect hosts. Ecology. Population dynamics. Abiotic factors. Chemical factors. Habrobracon hebetor (Braconidae): Parasite; Anagasta kuehniella (Pyralidae): Host. Anagasta kuehniella: Hymenopteran parasites, Habrobracon hebetor, Functional response, Population density, Fertilizers and pesticides, Insecticides; Habrobracon hebetor: Lepidopteran hosts, Anagasta kuehniella, Host seeking, functional response, Fertilizers and pesticides, Insecticides. ST Animalia, Arthropoda, Insecta, Hymenoptera, Apocrita, Terebrantia, Ichneumonoidea, Braconidae; Animalia, Arthropoda, Insecta, Lepidoptera, Glossata, Heteroneura, Pyraloidea, Pyralidae. Arthropods; Hymenopterans; Insects; Invertebrates; Lepidopterans. none