Two larval-pupal tachinid parasitoids; Goniophthalmus halli (Mesnil) and Senometopia (Eucarcelia) illota (Curran) were recorded from the pupae of Helicoverpa armigera (Hubner) on pigeonpea crop in Andhra Pradesh, India, between 1974 and 1996. Both the parasitoids enter in diapause following the signals received from their host and maintain close proximity in their development in nondiapausing and diapausing H. armigera populations. It is suggested that parasitoid diapause is induced by the physiological changes in late larval or pupal stage of the host and was observed in seasons when host diapause occurred and followed synchrony in terms of emergence for both the host and parasitoids. This is the first report of diapause in tachinid parasitoids from the southern region of Indian sub-continent
