What Happens When a Horse Fly Bites You?

Reviewed on 3/19/2021
Horseflies, also called the green-headed monsters, are small flying insects.
Horseflies, also called the green-headed monsters, are small flying insects.

Horseflies, also called the green-headed monsters, are small flying insects. Female horseflies feed on blood to reproduce. Like mosquitoes, female horse flies require a protein meal to produce eggs.

Like mosquitoes, horseflies have distinct mouthparts to feed on blood. The mouthparts of horse flies include:

  • Scissor-shaped jaw to tear the skin
  • Small hooks to help the horsefly lock in to suck better

However, unlike mosquitoes, which puncture and suck blood from their victim’s skin, horseflies tear the victim’s flesh. After using small hooks to lock in, the horse fly sucks blood from the skin. Thus, the saliva injected while biting causes a sharp burning sensation.

The saliva in the skin may also cause inflammation, itchiness, or bruise, around the site.

In some rare cases, a horsefly bite can trigger an allergic reaction, which includes:

What is a horsefly?

Horsefly resembles large house flies. As the name suggests, it most commonly attacks horses, cows, and other livestock. In horses, they may even spread life-threatening diseases, causing potential economic loss. They may even attack humans and pets.

How to treat horsefly bite?

To treat a horsefly bite, you can do the following things:

  • Cleanse the area.
  • Apply over the counter antiseptic spray or ointment to help clean the wound and decrease irritation and itchiness.
  • Take an antihistamine to reduce itching, if necessary.

Check out for signs of infection, such as:

  • Increasing redness
  • Swelling
  • Excessive pus
  • Foul odor
  • Any other unusual symptoms

You should immediately contact your physician if you observe the above symptoms.

Call 911 or your local emergency care number if you experience these symptoms:

How can I prevent horse fly bites?

Horsefly bites can be extremely painful. Hence, to prevent horse fly bites, you should:

  • Avoid places where flies are most active.
  • Cover exposed skin by wearing light-colored, long-sleeved shirts, pants, and hats.
  • Consider using a repellent effective against horsefly bites. Follow the manual carefully.
  • Install window and door screens.
  • Clear out piles of rubbish and decaying hay, straw, and other vegetation that attract flies.


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Health Solutions From Our Sponsors

National Pest Management Association. Horse Flies. https://www.pestworld.org/pest-guide/flies/horse-flies/

Medline Plus. Insect Bites and Stings. https://medlineplus.gov/ency/article/000033.htm

Washington State Department of Health. Biting Flies. https://www.doh.wa.gov/CommunityandEnvironment/Pests/BitingFlies

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