The bite from a larger specimen can be quite painful, especially considering the light, agile, and airborne nature of the fly. Unlike insects which surreptitiously puncture the skin with needle-like organs, horse flies have mandibles like tiny serrated scimitars, which they use to rip and/or slice flesh apart. This causes the blood to seep out as the horsefly licks it up. They may even carve a chunk completely out of the victim, to be digested at its leisure. When attacking humans they usually prefer the buttocks, legs, and feet, though they have been known to attack arms as well. The horsefly's modus operandi is less secretive than that of its mosquito counterparts, although it still aims to escape before pain signals reach their mark's sphere of awareness. Moreover, the pain of a horsefly bite may mean that the victim is more concerned with assessing and repairing the wound, than finding and swatting the interloper.
Horse flies are most active in hot weather, mostly in summer and autumn during the daylight hours. Most species also prefer a wet environment, which makes it easier for them to breed. Eggs are generally laid on stones close to water or on plant stems or leaves. On hatching, the larvae fall into water or moist earth, feeding voraciously on invertebrates, such as snails and earthworms, and small vertebrates.