Fly bites can cause symptoms such as swelling, itching, and redness. Numerous treatments can help relieve symptoms of a fly bite.

Although most people can recognize a bee, hornet, or wasp as being a risk for stinging, many perceive flies as harmless. However, there are several types of biting fly. Although not all flies bite, those that do can be an irritation and danger to some people.

This article will describe different flies that bite and how to recognize their bites, as well as some potential treatment options.

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There are six major types of biting fly in the United States. Some of these flies may have variations that are similar in appearance yet do not bite.

Most of the flies in this article do not cause harm other than the bite itself, though some can transmit disease or cause severe allergic reactions. These six biting flies are:

Biting midges

Biting midges are very small flies, that are less than 1/8 of an inch. People may also call them no-see-ums, punkies, or gnats.

They can cause small, itchy bites and currently, biting midges in the U.S. do not transmit disease. However, biting midges in South America can transmit a virus known as OropoucheTrusted Source. This virus can cause fever, joint pain, and body aches.

Black flies

Black flies are very small flies that have a humpbacked appearance. Some people may also call them buffalo gnats.

Male black flies do not bite, but females of most species feed on blood to produce eggs. This can result in painful bites, bleeding, itching, inflammation and swelling. In some cases, they may also cause allergic reactions in humans and livestock. They are not known to transmit diseases to humans.

Deer flies

These medium sized flies are usually the size of a housefly, but smaller than horseflies. They normally appear in the spring, have dark bands on their wings, and are predominantly either yellow-black or brown.

Deer flies can transmit tularemiaTrusted Source, or rabbit fever, to humans. This is a disease that occurs due to Francisella tularensis bacteria. Acquiring tularemia from a deer fly bite can cause a skin ulcer to appear at the site of the bite.

Horseflies

Horseflies are large and belong to the same family as deer flies. They can grow up to 1 1/4 inches in length. They may have green heads or be completely black. They usually live near water or other warm, wet locations.

Their bites rarely transmit diseases but can be painful due to how they bite the skin. Some people may also be allergic to horsefly bites.

Sand flies

Sand flies are small flies with hairy wings, which gives them a moth-like appearance. In the U.S., they are more common in the southern states.

Sand flies can transmit a neglected tropical disease called leishmaniasisTrusted Source. Symptoms can vary depending on the form of leishmaniasis. The most common form is cutaneous leishmaniasis, which can present with skin sores. Visceral leishmaniasis is a more severe form, and can cause fever, generalized illness, and anemia.

Stable flies

Stable flies are similar in size and coloration to house flies. As their names implies, they typically bite cattle and horses. However, they can also bites humans and can cause a very painful bite. Doctors do not think they can transmit diseases.

The size of the bite does not always matter when it comes to telling what fly bit a person. A very small fly can cause a very large, irritated bite.

A person can usually tell if a fly has bitten them if the following symptoms occur:

  • swelling
  • itching
  • redness
  • a small but visible hole in the middle of a bite-like bump

Sometimes, the symptoms may depend on the type of fly. For example, doctors know that black fly bites can cause lymph node swelling.

Some people may have an allergic response to a fly’s bite. Examples of allergic reaction symptoms include feeling dizzy and weak. A person may start to develop trouble breathing or swelling in different body areas.

Flies commonly make multiple bites in the same areas of the body.

To help diagnoseTrusted Source a fly bite, a doctor can examine a bite, or areas of biting, and may ask questions about recent activities.

For example, they may ask where the person has recently been, such as around rivers, lakes, or wetlands. They will consider the bite’s appearance and its location on the body.

A doctor may be able to determine the type of fly from where the person was at the time they received the bite, and where the bites are on their body.

Unless a person is having very severe symptoms, a doctor will not usually need to perform further testing to determine the bite type.

If a person receives a fly bite, they can try the following stepsTrusted Source to relieve any symptoms:

  • Take an over-the-counter (OTC) anti-inflammatory medication, such as nonsteroidal anti-inflammatory drugs (NSAIDs), to reduce discomfort.
  • Clean the area with water or soap and water.
  • Place a cool compress or cloth covered ice pack over the bite to reduce swelling and minimize irritation and pain.
  • Using antihistamines to reduce itching.

If a person experiences an allergic reaction to a bite, such as wheezing or hives, they should seek emergency medical attention.

If a person experiences symptoms of an infection after a fly bite — such as fever, nausea, headaches, or swollen lymph nodes — they should consult their doctor. This is because they may have an infection, such as tularemia, as a result of the bite.

When possible, a person should avoid spending time in areas where biting flies are common. Examples include marshlands, forests, shady areas, or locations that have very dense plant life.

Keeping the yard neat and well trimmed can also help minimize the amount of flies in the area.

In addition to these preventive steps, a person can also:

  • Cover their skin by wearing a long sleeved shirt, pants, and a hat. Ideally, these would be light colored, as dark colored clothing may attract flies.
  • Wear insect repellants, such as those that contain DEET or picaridin. However, these are not always effective against all biting fly varieties.
  • Wear a hat with protective netting, such as a beekeeper’s bonnet, when they know they will be in an area that has a lot of flies. This can help keep flies away from the person’s head, where they often like to bite.

Avoiding the outdoors at times of day when flies tend to bite, such as the late afternoon, can also help.

Fly bites can range from a nuisance to a severe occurrence.

If a person has an infected-looking bite or numerous bites on their body, they should seek medical attention.

Otherwise, at-home treatments to reduce inflammation and irritation can usually help relieve most symptoms.