Two enclosed, shallow-pit, egg-layer poultry houses in north-central Indiana were sampled to determine densities and parasitism of house fly (HF),Musca domesticaL., pupae during 1982 and 1983. Seven parasitoid species emerged from sampled pupae:Spalangia cameroniPerkins,Spalangia nigroaeneaCurtis,Spalangia endiusWalker,Spalangia nigraLatreille,Muscidifurax raptorGirault&Sanders,Nasonia vitripennis(Walker) (Hymenoptera: Pteromalidae), andAphaereta pallipesSay (Hymenoptera: Braconidae).S. cameroniwas the most abundant species, emerging from 78.8% of all parasitized pupae collected, and also was the only species collected during winter. Although HF pupae were relatively abundant during winter, active parasitism was not observed during late winter and spring months. A positive relationship between parasitism and nonviability of parasitized pupae suggested that host feeding by parasitoid adults may substantially contribute to HF mortality. Possible strategies to suppress densities of HF pupae by periodically releasing parasitoids are discussed.