Emergence behaviour of adult Trogus lapidator (Fabricius) (Hymenoptera, Ichneumonidae, Ichneumoninae, Heresiarchini) from pupa of its host Papilio machaon L. (Lepidoptera, Papilionidae), with a comparative overview of emergence of Ichneumonidae from Lepidoptera pupae in Europe

Unusually for Ichneumonidae, Trogus lapidator emerges through a hole in the pupal wing case of its papilionid butterfly host that is made largely by a liquid secretion that softens and disintegrates the host tissue. The mandibles are deployed to help spread the secretion, but only towards the very end of the emergence process are they used (and then only in a minor way) to enlarge the hole. Links to video clips showing the emergence of T. lapidator are provided. Photographs illustrating the nature of emergence holes left in Lepidoptera pupae by a range of Ichneumonidae and some Chalcidoidea are presented and discussed, contrasting with the emergence hole left by Trogus and close allies.