INTRODUCTIONThis protocol describes a standard method for collecting Nasonia wasps using “flyliver”: liver remains fed upon by fly maggots (e.g., Sarcophaga) and collected after the mature larvae have dispersed. The flyliver, which contains a volatile substance that is very attractive to the wasps, is placed in a large (~15-cm2) mesh bag hung in appropriate collection spots (e.g., near birds’ nests or under culverts). Within the large mesh bag is a smaller mesh bag placed abutting the flyliver and containing four to six Sarcophaga pupae. These retain the wasps, which will enter the bag and begin stinging the hosts. The mesh bags can be made with standard nylon window screening, or any other material with mesh width large enough to permit entry of the wasps.