Observations on Some Insect Predators of Black Flies (Diptera:simuliidae) of Algonquin Park, Ontario

Insect predators of black flies are common although their predatory acts are infrequently observed. Observations are presented on black-fly predation by various species of the dipterous families Empididae, Dolichopodidae, Ephydridae, and Tendipedidae. A case of cannibalism among larvae of Simulium venustum is reported. Other insect predators of black flies mentioned include various species of Trichoptera, especially species of the genus Hydropsyche; Hymenoptera; and Odonata. Non-insect predators of simuliids that are mentioned include spiders, and a leech, Haemopis marmorata (Say). In Algonquin Park, Ontario, larvae of species of the trichopteran genus Hydropsyche appeared to be the most important predators of simuliid larvae, while dance flies were the most important predators of adult black flies.