Larval Habitats, Development, and Parasites of some Tabanidae (Diptera) in Southern Ontario

Blood-sucking horse flies and deer flies of the family Tabanidae are important pests of livestock and man in Hastings County, Ontario. In a survey made during 1951-56, immatures of 29 species were collected and reared to obtain information on their insect parasites and other biotic control agents in different habitats. Most of the tabanid specimens were found at five sites where populations were high. The periods of pupation and emergence of Chrysops and of the larger tabanids are shown. The most numerous biotic agents found were two egg parasites, Trichogramma minutum Riley and Telenomus emersoni Girault. Parasites of the larva were a tachinid, Phorostoma novaeangliae (West) and Bathymermis sp., a nematode parasite of Chrysops spp. There were two pupal parasites: Diglochis occidentalis (Ashm.) (Pteromalidae) and Trichopria sp., probably tabanivora Fouts (Diapriidae). There is evidence that both these parasites attack the mature larva of the host.