Cuckoo Wasps (lat. Chrysididae)

Ecology and behavior

Members of the largest subfamily, Chrysidinae, are the most familiar; they are generally kleptoparasites, laying their eggs in host nests, where their larvae consume the host egg or larva while it is still young, then the food provided by the host for its own juvenile. Chrysidines are distinguished from the members of other subfamilies in that most have flattened or concave lower abdomens and can curl into a defensive ball (“volvation”) when attacked by a potential host, in the manner of a pill bug. Members of the other subfamilies are parasitoids of either sawflies or walking sticks and cannot fold up into a ball. Chrysidids are always solitary. They fly mainly in the hottest and driest months of summer in subtropical and Mediterranean climates. They favor dry areas and sandy soils; many species are confined to a narrow type of microhabitat where adults may rest or find hosts to parasitize, for example on bare soil or on dead wood where other solitary wasps have their nest holes. Some species visit flowers such as of the Apiaceae, Asteraceae and Euphorbiaceae. Chrysidid wasps are not only known for their parasitic behavior but also for their exceptional resilience to drought conditions, often remaining dormant for extended periods until suitable hosts become available. Some species have also developed specialized body structures, such as reinforced cuticles, to withstand the attacks of their often-aggressive host species.