INTRODUCTIONNasonia is a complex of four closely related species of wasps with several features that make it an excellent system for a variety of genetic studies. These include a short generation time, ease of rearing, interfertile species, visible and molecular markers, and a sequenced genome. Furthermore, its parasitoid lifestyle allows investigations of questions relating to parasitoid/host dynamics, host preference, and specialist versus generalist biology. It also can serve as a behavior model for studies of courtship, male aggression and territoriality, female dispersal, and sex ratio control. This protocol describes methods to count and/or collect Nasonia eggs. Fly hosts are placed in a foam plug such that only one oviposition site is available to the female wasp.