Life cycle ofSphecophaga vesparum(Curtis) (Hymenoptera: Ichneumonidae), a parasitoid of some vespid wasps

Abstract

The literature on the biology of Sphecophaga vesparum (Curtis) is reviewed. New data are added and the life cycle is outlined. Winged adults emerge from yellow, overwintering cocoons from one to four springs/summers after the season in which the cocoons were formed, and may live for up to 3 weeks. The species is at least facultatively deuterotokous, but mating can occur. Within wasp nests, winged and brachypterous females prefer to oviposit into cells within which host pupation has most recently occurred. The species is ectoparasitic on wasp immatures within capped cells. Both female morphs lay three kinds of eggs: those that give rise to white cocoons and then brachypterous females within 13 days, those that give rise to weak, yellow cocoons that produce winged females and possibly males within 15 days, and those that give rise to resistant, yellow, overwintering cocoons. Many generations may originate from one invasive winged female in one year. The species is very well adapted to take maximum advantage of its host's life cycle. Productivity of individual females, whether fertilisation occurs, and the mode of entry of winged females into wasp nests, have yet to be determined.