none The present investigations confirm that the functional virginity of Trioxys indicus is less than 5 minutes. However, longer pre-oviposition period following insemination significantly enhances the proportion of fertilised eggs, which is an adaptation of a potent bioagent. The production of male offsping by mated female, i.e., the inhibition of fertilisation, as a by-product inherent in the physiology of the reproductive system is also supported by this work. Reproduction; Reproductive behaviour; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Ecology; Population dynamics; Population structure Trioxys (Binodoxys) indicus (Braconidae); Oviposition; Preoviposition period; Hemipteran hosts; Aphis craccivora; Female parasite preoviposition period, effects on progeny sex ratio; Population sex ratio; Female biased progeny, preoviposition period effects Aphis craccivora (Aphidoidea); Hymenopteran parasites; Trioxys (Binodoxys) indicus; Female parasite preoviposition period, effects on progeny sex ratio