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Horsefly Bites – How to Tell If You’ve Been Bitten

Last Updated: 09.08.20


In the war against these annoying nuisances, you must have a spray that kills flies efficiently. Most of the flies can’t do a lot to hurt people as they can’t bite or sting, but the horseflies are known to bite people. People who have been bitten will get painful hives on the skin. These lesions will take considerable time to heal, and their infection should be prevented.


How to identify a bite

Compared to other insect bites, horsefly bites are quite painful and usually, it takes a lot of time for them to completely heal. These consequences are provoked by the horseflies’ way of biting. 


Horsefly bite’s characteristics

The bite looks more like a cut than a small hole because the horsefly’s mouthparts move like a scissor to make a cut in the skin. Horseflies don’t feed like mosquitos as they can’t suck the blood through a trunk, but they wait for the blood to come out of the wound and they clean it. 

Besides the skin cutting, they cause additional pain to their victim as they anchor themselves to the skin using small hooks placed close to their mouthparts. Usually, the bitten skin becomes red and is surrounded by a raised area of skin, known as a hive or weal.

A horsefly bite could become infected and it usually takes a day or two for this to happen. You should check if the redness of the skin is spreading as this is one of the biggest signs of an infection. Also, watch out for puss or any discharge coming from the bite.



Are horseflies harmful?

Despite the unpleasant effects of being bitten by a horsefly, there are no harmful effects for humans. The only disease transmitted by horseflies is the swamp fever, which can be deadly for horses.


How to treat a horsefly bite

Taking care of a horsefly bite is similar to treatment for other types of insect bites. The major concern about horsefly bite treatment is to prevent the wound from getting infected. How the horsefly damages the skin causes the wound to be more likely to become infected.

If you got bitten by a horsefly, don’t scratch the wound as it will make it worse and will increase the chances of developing an infection. Gently clean the skin with soap and warm water using a cloth or a piece of cotton wool. 


If the skin is swollen

If the bite has started to swell, you should apply an ice pack or a cold compress. This will cause the blood vessels to shrink so the swelling will reduce as fewer blood cells will rush to the area. Also, antihistamine tablets could help calm the swelling.



If the bite is painful

If the affected area becomes painful, you could use over-the-counter painkillers to ease the discomfort. Paracetamol and ibuprofen are good options in this case. If the bitten person is younger than 16 years old, aspirin should be avoided.


It the bite is itchy

If the wound caused by the horsefly becomes irritable and you feel like scratching it, apply some cream or lotion. Ask the pharmacist for an over-the-counter treatment, including crotamiton or hydrocortisone cream or ointment. It the skin is very irritable, ask for some antihistamine tablets.

Don’t try to use a solution made of bicarbonate of soda and vinegar as it will have no useful effect. Also, the horsefly’s mouthpiece doesn’t get stuck on people’s skin so there is no need to look after it.


Manifestations of horsefly reactions

In general, there is no serious allergy caused by horsefly bites but it can cause dizziness or wheezing. Also, look out for swollen skin close to the eyes or lips. 

A more severe reaction (known as anaphylaxis) is uncommon but represents an emergency. You should call for an ambulance if the bitten person shows any signs of anaphylaxis. This may include difficulty breathing or swallowing, nausea, diarrhea, or tongue and throat swelling.  

People who have been bitten before by a horsefly could have a severe allergy to horsefly bites. Their immune system prepares to shield the individual against other possible instances but it becomes over-sensitive to future bites.

In case you developed a severe allergy as a result of a previous bite, you might need to carry an emergency epinephrine injection to take care of any reactions caused by future bites.


Where do horseflies live?

Horseflies generally live close to woodlands and you can find them in rural areas, where they feed on bigger animals. But you can see them in urban zones near water-rich breeding places, such as lakes or ponds. They are present across North America and are usually seen during daylight and in days without wind. 



What do they look like?

We talked about the effects of their bites and now you should be aware of their appearance so you can avoid them. First of all, they are bigger than a housefly. Adult horseflies have wide bodies with prominent compound eyes and short antennae. 

You could tell if a horsefly is a female or a male by looking at the eyes. If the eyes are widely separated, it is a female. If the eyes are very close to each other as they are almost touching, it is a male. Their body coloring is dark but they have stripes on their bellies and chest. 


A horsefly’s habits

Adult horseflies can fly more than 30 miles as they are good, strong fliers. However, they do not dissipate widely. Most of the time, they attack dark and moving animals. These insects generally rest on trails and roads, especially in forested areas, where they wait for their next host. Also, light attracts them so they might gather around windows or outdoors light bulbs.


Why do horseflies bite other animals?

Adult horseflies generally eat nectar, but females need a meal consisting of blood so they can support the egg production as part of an efficient reproduction. Only female horseflies have the necessary mouthparts required for biting through animal skin. 

Horseflies must feed on the blood of large animals such as cattle, horses, and humans as part of their life cycle. If you thought mosquito bites are painful, you haven’t experienced a horsefly bite. The horsefly’s’ bite is usually hurtful, especially in big specimens as they use their mouthparts to tear and fold the skin.


Horseflies don’t quit

Almost every farmer could tell you that horseflies are insistent and will usually keep on biting a host until they either obtain enough blood meal or are killed. Horseflies are well-known to chase their host for a short period of time. 

When entering the reproduction stage, female horseflies need approximately 0.5 milliliters of blood to sustain egg production. This is a big amount of blood compared to their size and they can eat up almost 200 milligrams of blood in several minutes. 

Their feeding process is somehow similar to how other sucking arthropods (ticks or mosquitos) feed themselves with the host’s blood. The horsefly is uniquely adapted to take as much blood as needed. It can release a chemical substance to prevent the blood from clotting at the surface of the skin. Horseflies were used in traditional Chinese medicine because of these anti-clotting attributes.


How to prevent horsefly bites

In general, it is difficult to avoid interacting with horseflies during the summer as their habitats are widespread. However, there are some workable steps you could follow in order to reduce the possibility of getting bitten.

When engaged in an outdoor activity, wear pants and long-sleeved shirts to keep the skin covered. Also, it helps if the clothing is light in color. Avoid walking through fields covered in tall vegetation but if it’s necessary, wear shoes and long pants. 

Avoid cosmetic products with a strong scent as this could attract flies. Try to stay away from the horsefly’s breeding zones during the summer. So don’t make picnics around lakes or ponds. 

You will not have a lot of success using insect repellent against horseflies, but it will keep away mosquitos, which might be present in the same areas. If you are looking for a good repellent, search for repellents with 50 percent diethyltoluamide (DEET).


Hot to get rid of them

You can use a DIY insect spray to kill these annoying fliers. One solution is to make a common soap spray which you can use to suffocate most insect pests. Pour 2 cups of vinegar, 1 cup of warm water and 4 tablespoons of dish soap into an empty spray bottle and give it a gentle shake. You can spray plants with this mixture without having to worry about side effects. 



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