The Asilidae (Diptera) of Bosanquet (northern Lambton County, Ontario) are surveyed. Forty-one species are recorded. Twelve species are published for the first time from Canada: Atomosia puella, Cerotainia albipilosa, Cerotainia macrocera, Holcocephala calva, Holopogon (Holopogon) oriens, Laphria canis, Laphria divisor, Laphria grossa, Lasiopogon opaculus, Machimus notatus, Machimus sadyates, and Neomochtherus auricomus. These species plus the following four are new to Ontario: Laphystia flavipes, Lasiopogon tetragrammus, Machimus novaescotiae, and Proctacanthella cacopiloga
