The seasonal and geographical distribution of Tabanidae in Manitoba was investigated. Females were trapped in 27 localities in Manitoba by means of a horse-fly trap developed at the University of Manitoba.
The species composition varies in different areas. Wet, swampy, forested areas yield a much greater variety of species than drier farming areas.
The first tabanids appear during the last week of May and by the end of July very few are active. The seasonal distribution of species in some of the trapping sites was plotted. Hybomitra metabola (McD.) and H. nuda (McD.) are the earliest species that occur in large numbers in areas where they are found. In the latter half of June the summer species such as H. lasiophthalma (Macq.), H. frontalis (Wlk.), H. epistates (O.S.), H. typhus (Whitn.), Tabanus similis Macq. and the Chrysops species appear in large numbers.