Horse fly against a white background - Keep horse flies out of your home with Kona Coast Pest Control in Kailua Kona

Horse Fly

Actual Size: ¾  to 1 ¼”

Characteristics: Gray or black in color with clear wings and bulging eyes.

Legs: 6

Antennae: Yes

Wings: Yes

Habitat: Typically found in proximity to water and damp soil within brushy or low-lying pasture zones.


  • Bites can be very painful resulting in visible wounds.
  • Known to feed on the blood of mammals, including horses and humans.
  • Significant livestock pests with their painful and persistent biting behavior. 
  • Attracted to dark colors and are known to be visual hunters.
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Horse Flies in Kailua Kona

Horse flies, known for their considerable size and weight, are incessant pests affecting wildlife, livestock, and humans. Their blood-sucking behavior gives rise to concerns about the potential transmission of disease agents. These insects are infamous for targeting a variety of mammals, including horses, mules, cattle, hogs, dogs, and humans. Horse flies can be identified by their dark wing bands and eyes resembling those of deer flies. An assault by just a few of these persistent flies can make outdoor work and recreational activities into a miserable ordeal.

Horse Fly Habitat

Horse flies tend to inhabit areas near water habitats that are conducive to larval development. The majority of these flies find their habitat in brushy or low-lying pasture areas near creeks, streams, or reservoirs, where the presence of damp soils supports the growth of their immature stages. Freshwater wetlands, saltwater marshes, and open spaces within forests are part of their natural habitats. These insects thrive by burrowing into the sand or gravel substrate of the water body they reside in.

Horse Fly Behaviors, Threats, or Dangers

People may experience bites from female horse flies, as these insects have the ability and tendency to bite, causing pain on any part of the body. The resulting bites often lead to visible bleeding wounds. The application of general first-aid type skin creams may provide relief from the discomfort. In rare cases, allergic reactions may manifest, presenting symptoms such as hives and wheezing. Evidence in the western U.S. suggests the involvement of a horse fly in transmitting a bacterium causing tularemia, known as deer fly fever or rabbit fever. These flies are well-known livestock pests with a painful and relentless biting behavior. Severe attacks can cause declines in weight for beef cattle and lower milk output in dairy cattle. If you are dealing with a horse fly issue on your property, contact your local fly exterminators.