Relative abundance and seasonal distribution of Tabanidae (Diptera) near Guelph, Ontario

The results are presented of a survey of tabanids in 4 habitats near Guelph, Ontario, in 1971-73, using traps baited with carbon dioxide. Nearly equal numbers of species were taken at the 4 places, and females of 15 species of Chrysops, 12 of Hybomitra, 6 of Tabanus and 1 of Atylotus are recorded. The relative abundance and flight periods are reported for each. C. frigidus O.-S. was the most abundant chrysopine and H. lasiophthalma (Macq.) the most abundant tabanine; their abundance was directly related to the degree of soil wetness, differing from that of T. similis Macq. and T. quinquevittatus Wied. which was related inversely to these types of habitat. The flight period of nearly 85% of the tabanid population, consisting mainly of C. frigidus, H. lasiophthalma and H epistates (O.-S.), lasted from the end of May till mid-July. T. quinquevittatus, T. lineola F. and H. epistates were present until mid-September.