Effect of food plants on the functional response of parasitoid Campoletis chlorideae, Uchida (Hymenoptera: Ichneumonideae) is an effective bio-control agent against Helicoverpa armigera, Hubner (Lepidoptera: Noctuidae). an attempt has been made to find out the effect of three food plants of H. armigera viz Cicer arietinum, Pisum sativum and Cajanus cajan on functional response of C. chlorideae. C. chloride is allowed to do it functional activities like antenalen counter, stings and number of off springs emergence on three selected food plants reared host at different host densities viz 2,4,8,16,32 and 64 and data obtained is subjected to ANOVA. It is observed that antenalen counters, stings and no. of offspring emergence of parasitoid increase significantly with the increase of host densities reared on three food plants and found to be maximum on host reared on C. arietinum followed by P. sativum and C. cajan. It means this parasitoid C. chlorideae could play a role in the integrated control of H. armigera.