Seasonal abundance and species diversity of adult Tabanidae (Diptera) at Lake Lansing Park-North, Michigan

A 2-year study was undertaken to determine the seasonal abundance and diversity of adult deer flies and horse flies, to compare 2 methods of sampling (Malaise trap and sweep net), and to estimate attack rates by tabanids on people at Lake Lansing Park-North, Ingham County, Michigan, USA, in 1990 and 1991. Tabanids were sampled using dry ice-baited Malaise traps, and by making overhead sweeps with a standard insect net while hiking a trail. Hybomitra spp. (299 individuals of 9 species) peaked in abundance in mid-May to early June in both years. Chrysops spp. (11 675 individuals of 14 species) and Tabanus spp. (324 individuals of 8 species) peaked in early-to-late July in both study years. Peak abundance for Chrysops and Tabanus spp. occurred earlier in 1991 than 1990, probably because the spring of 1991 was warmer. There were 6 new species records for Ingham County: C. celatus, C. sackeni, H. hinei, H. minuscula, H. pechumani and T. fairchildi. More individual Hybomitra and Tabanus were taken by Malaise traps (77.3% for Hybomitra; 76.2% for Tabanus) than by netting (22.7% for Hybomitra; 23.8% for Tabanus). In contrast, sweep netting yielded more individual Chrysops (98.3%) than Malaise traps (1.7%). Tabanid attack rates on people hiking the trail exceeded 1000 per hour on one occasion each year, at mid-season. C. vittatus was the most abundant tabanid in all collections (82.7% of all flies in 1990, 74.0% in 1991). Other common species were C. aberrans, C. univittatus, C. frigidus, C. celatus, C. sackeni, T. lineola, T. pumilus, T. sackeni, H. epistates, H. lasiophthalma and H. illota.