There are many species of deer flies as well as their close relatives, the horse flies. Deer flies are usually smaller and more colorful than horse flies. Pupation occurs in drier soils away from the water-logged area. Tabanid larvae are predaceous on other aquatic insects and small animal life. Adult tabanids vary in their periods of activity.
Deer flies are usually most active in the early morning and late evening.
Horse flies are active all day long usually. Female tabanids are blood feeders and are the biting pest. Male tabanids feed on plant juices or excretions.