The American Horse Fly is known as Tabanus americanus, and is between 3/4-1 1/8" (20-28mm) long. They have a large, broad body, their head is tan to ash-gray between their large green eyes. The American Horse Fly has reddish brown antennae, a brownish to black thorax with gray hair, and an abdomen that is blackish red-brown. Their wings are a smoky brown to black near the base.
- The male eats pollen and nectar while the female takes blood of large mammals. Larvae preys on aquatic insects and other small animals.
- Egg masses are attached to plants overhanging fresh water, into which larvae drop. Larvae stay in the muddy bottom and they pupate in spring. Males are short-lived, but females may survive until fall.
- The like to live mostly near swamps, marshes, and ponds.
- Range Newfoundland to Florida, west to Texas and northern Mexico, north to Canadian Northwest Territories.
- Warning When the female bites, the wound inflicted often continues to bleed for several minutes because the fly's saliva contains an anticoagulant that prevents clotting. A single animal may suffer a debilitating loss of blood if many of these insects attack it.