Horse flies possess one of the fiercest bites of any fly species. Unlike the often nearly painless bite of the mosquito, horse flies are equipped with scissor-like mandibles that tear flesh. While male horse flies feed on pollen and are pollinators, females feed on blood in order to assist in egg development.
The peak of horse fly season coincides with warm weather, and these flies are most active in summer and early fall. They prefer wet areas, congregating most commonly near the shores of lakes and at beaches. Horse flies are attracted to dark objects and use their complex, compound eyes to locate prey. Horse flies appear to be attracted to certain odors, as well as to carbon dioxide. Female horse flies lay eggs on rocks and plants near water. Larvae then prey on invertebrates such as snails and grubs, which they find by burrowing into the soil.