Muscidifurax zaraptor Kogan and Legner, M. raptorellus Kogan and Legner, and Spalangia cameroni Perkins were released bi-weekly in two facilities at a broiler-breeder egg production farm in Arkansas during 2003 and 2004. Of the recovered house fly, Musca domestica L., sentinel pupae, 18.8% were parasitized in 2003, with M. zaraptor being the dominant species (66.8%) and M. raptorellus contributing 6.9% of the parasitism. The release of M. raptorellus did not result in substantial parasitism in sentinel house fly pupae until the second year of study when M. raptorellus was the most dominant species, contributing approximately 61.9% parasitism. At the non-release farm, 13.9% of the sentinel house fly pupae were parasitized, with S. cameroni and M. zaraptor dominating in 2003. Parasitism at the control farm decreased to 3.4% in 2004. It appeared that sustained releases of parasitoids at the release farm over two years provided a significant increase in house fly pupal parasitism when compared to the percentage of pupae parasitized at the non-release farm. Of the sentinel Hydrotaea aenescens (Wiedemann) pupae recovered from the release farm, 9.3% were parasitized in 2003. Filth fly data indicated that the combined predator activity of H. aenescens and sustained parasitoid releases reduced M. domestica to a level well below the treatment threshold. In addition, the sustained release of parasitoids reduced H. aenescens numbers to below the treatment threshold of 100 filth flies per sticky ribbon per week by 9 wk during the latter part of the filth fly season during 2003 and 2004.