PARASITOIDS (HYMENOPTERA, PTEROMALIDAE, ICHNEUMONIDAE) OF FILTH FLY (DIPTERA, MUSCIDAE) PUPAE AT DAIRIES IN ALBERTA

Filth fly pupal parasitoids were surveyed for 2 yr at four dairies in southern Alberta. Seven parasitoid species were recovered. Muscidifura x raptor Girault and Sanders, M. zaraptor Kogan and Legner, and Tricho malopsis sp. were the most abundant and were recovered in both years. Other species were Urolepis rufipes (Ashmead), Phygadeuon sp. Spalangi a cameroni Perkins, and Dibrachys cavus (Walker). Parasitism of intact pupae was generally <2%, but exceeded 30% on one occasion. Parasitoid s were active from May to October, with most activity during August. S easonal patterns for M. raptor and Trichomalopsis sp. were not consist ent both years and were probably influenced by excessive rainfall duri ng June 1991 and relatively low levels of parasitism. Parasitoid activ ity increased with increasing temperature and was negligible at temper atures below 11 degrees C.