black fly

A black fly, or blackfly, is an annoying pest that bites and sucks blood. Like mosquitos, females gain nourishment from feeding on the blood supply of mammals. They lay eggs in running water and the larvae attach themselves to rocks. They pupate under water and emerge in a bubble of air as flying adults. They thrive in cool wet weather. Bites are most often found on the head, neck, and back, but they also land on arms and legs. Repellents provide some protection, but proper clothing, including nets over the heads such as those used in beekeeping, can help.