The solitary, pupal parasitoids Spalangia spp. Muscidifurax raptor oviposited supernumerary eggs on house-fly pupae exposed at 3 poultry farms in north central Florida. The percentage total parasitoidism at the 3 sites was 23.7%, 33.6%, and 77.5%, while the percentage of the hosts containing supernumerary parasitoids was 6.2%, 10.7%, and 55.8%, respectively. The average number of parasitoids found per parasitoidized pupa ranged from 1.45 to 2.96. The parasitoids did not show a density-dependent response to spatial variation in host density. Among aggregates of hosts that contained at least 1 parasitoid, percentage total parasitoidism either decreased as host density increased or was unrelated to host density. When total parasitoidism was low, females tended to avoid already parasitoidized hosts. When total parasitoidism was high, more of the hosts contained multiple parasitoids than a single parasitoid.