The population dynamics of four parasites of house fly,Musca domesticaL., pupae,Spalangia endiusWalker,S. cameroniPerkins,Muscidifurax raptorGirault&Sanders, andM. zaraptorKogan&Legner, and their host were simulated in a computer model written in the C language. The model incorporates nonlinear temperature-dependent development, effects of host–parasite ratio on host mortality and parasitism, competition between adult parasites, and options for various insecticide, manure removal, and parasite release strategies for fly control. Examples of the results of simulating parasite releases and pesticide applications are presented.