Horse Fly

Controlling Horse Flies in Your Home or Business

General Information

The horse fly is a large, bloodsucking fly known for its painful bite. The common name of the horse fly applies to a variety of species of biting flies. Most horse flies are classified under the genera Tabanus, Hybomitra, and Haematopota.

Found across the globe, the horse fly is a common pest in New England.

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Appearance & Identification

What Does a Horse Fly Look Like?
Large and robust, the horse fly can measure up to an inch in length. A large pair of eyes dominates the head, with females exhibiting separated eyes and males having contiguous eyes.

Horse flies are black or dark brown in color and have translucent, body-sized wings. Larvae are spindle-shaped and creamy white or tan in color.

Habits/Habitat

Horse flies are common in wet sites like wooded, swamp, and beach environments. The pests are active during the warm summer months, and female flies are usually seen during the daytime searching for blood meals.

Attracted to warmth and carbon dioxide from the breath of living creatures, female horse flies will leave breeding sites to seek out hosts.

Diet

What Does a Horse Fly Eat?

Female Horse Flies

Female horse flies feed on blood in order to gain a protein that aids in egg production. Horses, cattle, and humans are common hosts to these blood-feeding insects.

Male Horse Flies

Male horse flies primarily feed on pollen and nectar.

Larvae

During development stages, larvae feed on decaying organic matter and soft-bodied animals such as earthworms and grubs.

Reproduction

Female horse flies deposit eggs in the soft mud of aquatic and semiaquatic environments like:

  • River banks
  • Marshes
  • Along the edges of ponds

Females lay between 25 and 1,000 eggs at a time, and eggs usually hatch within a week. Horse flies remain as larvae for one or two years (capable of overwintering in mud substrate) and pupate in the spring and early summer months.

A summertime pest, the adult horse fly has a lifespan of one to two months.

Problems Caused by Horse Flies

Female horse flies use sharp, blade-like jaws to slash open skin and feed on blood. Unlike mosquito bites, horse fly bites are initially painful and feel like a sharp prick. Bite sites typically develop into red lumps and may itch for one to two days.

Horse flies are not known to pass diseases to humans, but secondary infections may occur from irritated bites (scratching). Cattle farmers also find the pests troublesome because excessive bites on livestock can reduce the production of dairy cows and stunt the growth of beef cattle.

Signs of Infestation

Homes near water are most susceptible to infestations of horse flies. Seeing multiple flies darting around the home may indicate an infestation.

The pests generally do not breed inside of structures, and prolonged horse fly infestations are an uncommon occurrence.

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How to Get Rid of Horse Flies & Prevention

Homeowners want exclude horse flies from their homes by keeping windows and doors closed and sealing up any cracks and openings into the home. Traps may also be used to combat the pests, but the practice is not an efficient method of control.

Pesticide control methods (insecticide sprays or baits) are also not completely effective because breeding grounds are usually away from structures the flies inhabit.

Individuals expecting to encounter horse flies outdoors may wish to cover the skin with long clothing to prevent bites. For serious infestations, calling professional control teams is the best way to get rid of horse flies.