none The aphid Aphis craccivora was reared on Cajanus cajan, Dolichos lablad and Solanum melongena and the effect of these host plants on the sex ratio of Trioxys (Binodoxys) indicus have been discussed which proved to be density dependent. The decrease in the sex ratio i.e., production of greater number of males than females, is maximum in case of S. melongena and maximum in C. cajan reared aphids. The texture of the leaf surfaces of the host plants have been attributed to influence the sex ratio. Results show that for obtaining maximum female progeny, fewer release of parasitoids at any release site will be better. During off season, Dolichos lablab (perennial plant) is suggested for the mass rearing of the parasitoid when the ideal host plant C. cajan is not available in the field. Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Ecology; Population dynamics; Population structure; Land and freshwater zones; Oriental region Trioxys (Binodoxys) indicus (Braconidae); Hemipteran hosts; Aphis craccivora; Hosts plant host on parasite sex ratio; Host parasite relationships; Population sex ratio; Hemipteran hosts plant host effect; India; Hemipteran hosts plant host effect on parasite sex ratio Aphis craccivora (Aphidoidea); Hymenopteran parasites; Trioxys (Binodoxys) indicus; Plant host effect on parasite sex ratio; Host parasite relationships; India; Plant host effect on hymenopteran parasite sex ratio