Both genders will drink flower nectar and eat pollen, but females add to their diet by consuming blood from animals. She will lay 50 or so fertilized eggs in a muddy area, near a lake, creek, pond or stream. Larvae (maggots) hatch and will molt several times before taking on a winged adult form. They feed on decaying matter and spend some time feeding on debris in water before migrating to land.
The most active months for biting attacks are May and June in the south. They are most active between afternoon and dusk. Large congregations live near water, which is necessary for part of the larval life stage. They can be found bothering people and animals in backyards, open fields, parks, farms and forest edges near water.