ABSTRACT
The management and operation of midwestern beef cattle confinements often results in substantial fly production. Further, these activities generally do not favor the build-up of naturally occurring pathogens and parasites. Little information is available on the pathogens of house flies or stable flies. The fungus, Entomophthora muscae, is the only pathogen observed to produce epizootics in house flies, and no epizootics have been observed in stable flies on midwestern confinements. Predators apparently have a significant impact on immature stages of these flies, but to date little is known about the species involved or the factors that influence their effectiveness as biological control agents. Pteromalid wasps parasitize the pupal stage of these flies and can be easily produced in large numbers. Because the numbers of these wasps begin at low levels and generally increase during the fly season, efforts have been made to enhance this build-up. Methods of establishing protected cohorts of house fly pupae in the field as host sources are discussed.
