Horse Fly

Category:

Actual Size: ¾  to 1 ¼”

Characteristics: Black or gray; clear wings, bulgy eyes.

Legs: 6

Antennae: Yes

Wings: Yes

Habitat: Found near water and damp soil in brushy or low-lying pasture areas.

Habits:

  • Similar to deer flies; do not breed inside structures.
  • Bites can be very painful resulting invisible wounds.
  • Significant livestock pests with their painful and persistent biting behavior.


Horse Flies in St. Louis

Horse flies and deer flies are large, heavy-bodied insects that are persistent pests of wildlife, livestock, and humans. Their blood-sucking habits also raise concerns about the possible transmission of disease agents. They are notorious pests of horses, mules, cattle, hogs, dogs, and other mammals, including humans. Deer flies, which commonly bite humans, are smaller with dark bands across the wings and colored eyes similar to those of horse flies. An attack by a few of these persistent flies can make outdoor work and recreation miserable.

Horse Fly Habitat

Horse flies and deer flies can be found near aquatic habitats that support larval development. Most horse flies and deer flies are found in brushy or low-lying pasture areas near creeks, streams, or tanks that provide damp soils in which the immature stages develop. Natural environments include freshwater wetlands, saltwater marshes, and open areas within forests. They survive by burrowing down into the sand or gravel substrate of the water body they inhabit.

Horse Fly Behaviors, Threats, or Dangers

Female horse flies and deer flies can and will bite people, and the painful bites may occur on any part of the body. The bite often results in visible bleeding wounds and general first aid-type skin creams may help to relieve the pain from bites. In rare instances, there may be allergic reactions involving hives and wheezing. These flies are significant livestock pests with their painful and persistent biting behavior. Heavy attacks can lead to reductions in weight gains of beef cattle, and reduced milk yield in dairy cattle. If you are dealing with a horse fly issue on your property, contact your local fly exterminators.