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Horse Fly: How to Identify and Get Rid of Horse Flies

Horsefly sipping nectar on a yellow flower

Horse flies are a common pest that many people encounter, especially during the warm summer months. These insects are known for their painful bites and their persistent nature, often causing distress to both humans and animals. They are found worldwide, with over 3,000 species known to exist.

Horse flies are not just a nuisance, they also pose a risk to livestock and horses, as they can transmit diseases. They are attracted to movement, shiny surfaces, carbon dioxide, and warmth. This makes outdoor activities, like hiking or horseback riding, particularly susceptible to horse fly attacks.

Despite their name, horse flies do not only target horses. They can bite humans and pets, causing discomfort and sometimes allergic reactions.

In this article, I will explain horse flies in-depth and cover not only what they are and what they look like, but also also their habits and how to protect yourself against horseflies and get rid of them.

What Is A Horse Fly?

A horse fly is a large, robust type of fly that belongs to the family Tabanidae. They are known for their painful bite and are commonly found in rural areas, particularly near bodies of water where they lay their eggs. Horse flies are not only a nuisance to humans, but they are also a significant pest to livestock, including horses, hence their name.

Closeup view on the head of a horse fly

Photo Credit: Shutterstock.

Horse flies are easily distinguishable due to their size and appearance. They are considerably larger than the common housefly, with females generally being larger than males. They have a pair of large, brilliantly colored eyes that cover most of their head, and their bodies are gray or black in color.

The female horsefly is particularly notorious. Unlike their male counterparts who feed on nectar and pollen, female horse flies feed on blood, which they require for reproduction. Their bite can be extremely painful due to their scissor-like mandibles which cut into the skin, causing blood to pool which they then lap up.

While they are most active during hot, sunny days, horse flies can be a problem all year round in warmer climates. Their bites not only cause pain and discomfort but can also transmit diseases and parasites, making them a significant concern in pest control.

Life Cycle of a Horse Fly

Understanding the lifecycle of a horse fly can be crucial in decisively managing and controlling their population. The lifecycle of a horse fly comprises four key stages: egg, larva, pupa, and adult.

The process begins when a female horse fly lays her eggs on vegetation near bodies of water, which is their preferred breeding ground. These eggs are usually laid in clusters and are characterized by a dark color. The eggs hatch into larvae within a week, depending on the environmental conditions.

Adult horsefly laying eggs on a green leaf

Photo Credit: Shutterstock.

The larval stage is the longest in the horse fly’s lifecycle, often lasting up to three years. During this period, the larvae remain mostly aquatic or semi-aquatic, residing in damp soil or water. They are predatory by nature, feeding on other insects and small invertebrates.

Once the larvae have grown sufficiently, they enter the pupal stage, which can last from one to three weeks. During this stage, they remain stationary and undergo a transformation process, metamorphosing into adult horse flies.

Dorsal view of an adult horsefly on a green leaf

Photo Credit: Shutterstock.

The adult stage is the final stage in the lifecycle. Adult horse flies are known for their aggressive biting behavior, with females feeding on the blood of animals, including horses, cattle, and sometimes humans.

The males, on the other hand, feed primarily on nectar. The lifespan of adult horse flies is relatively short, usually not exceeding a few weeks.

What Do Horse Flies Look Like?

Horse flies are a unique species of fly that are easily distinguishable due to their distinctive features. They are larger than the common housefly, with females usually measuring between 0.75 to 1.25 inches in length, while males are slightly smaller.

Their bodies are dense and dark, often black or gray, and their large, compound eyes are one of their most distinguishing characteristics. These eyes are usually brightly colored with intricate patterns, which can range from green to purple hues.

Macro shot of a horsefly

Photo Credit: Shutterstock.

Their wings are large and clear, with a span that can reach up to 25mm. The wings often have dark patches or bands, which can be used to identify different species of horse flies. The legs of the horse fly are usually long and slender, and they end in sharp claws which they use to grip onto their host while feeding.

Horse flies have a robust, sponge-like proboscis or “snout,” which they use to bite and feed on blood. In females, this proboscis is equipped with blade-like mandibles designed to cut through the skin of their host. This is a characteristic unique to biting flies and is part of what makes horse flies such a nuisance to humans and animals alike.

It’s important to note that horse flies can vary in appearance depending on their specific species. There are over 3000 known species of horse flies worldwide, each with their own distinctive features. However, the general description provided here should help you identify a horse fly if you encounter one.

Where You Can Find Horse Flies?

Horse flies are a common pest in many parts of the world and can be found in a variety of habitats especially wooded areas. They are particularly prevalent in rural and agricultural areas, where they are often a nuisance to livestock.

However, these insects are not exclusive to the countryside; they can also be found in urban areas, particularly near bodies of water.

Horsefly perching on a green plant

Photo Credit: Shutterstock.

Horse flies are attracted to heat and movement, which is why they often target large mammals such as horses and cattle. They are also known to bite humans, especially in areas where their natural habitats have been disrupted.

In terms of geographical distribution, horse flies are widespread across the globe. They are commonly found in most areas of the United States and North America, Europe, and Asia, but can also be found in parts of Africa and South America. In the United States, they are particularly common in the humid Southeast.

These pests are most active during the day, particularly in the hot summer months. They tend to lay their eggs in damp soil near bodies of water, which is why you’ll often encounter them near ponds, marshes, and swamps.

Horse Fly Habits

Horse flies are known for their aggressive behavior and painful bite, making them a nuisance for both humans and animals. They are diurnal creatures, meaning they are most active during the day, particularly in hot, sunny conditions.

Horse flies are attracted to movement, shiny surfaces, carbon dioxide, and warmth. This explains why they are often found buzzing around sweaty humans and animals. They are especially prevalent near bodies of water, where they lay their eggs.

Unlike many insects, horse flies are persistent hunters. A horse fly will chase its target relentlessly, not easily deterred by attempts to swat it away. This is because they require blood meals for reproduction. Female horse flies feed on blood, while the males are more interested in nectar.

Selective focus of a horsefly with another insect

Photo Credit: Shutterstock.

Interestingly, horse flies are strong fliers and can travel several miles from their breeding sites in search of food. They tend to attack moving objects and will often target large, dark animals such as horses, cattle, and deer. However, they are not averse to biting humans if given the opportunity.

Their bites can be extremely painful because instead of piercing the skin, horse flies have scissor-like mandibles that cut into the flesh to create a pool of blood which they then lap up. This method of feeding can lead to significant blood loss in animals if there is a large infestation.

Do Horse Flies Bite?

Yes, horse flies are notorious for their painful bites. Unlike many other insects, horse flies have scissor-like mandibles that cut into the skin, creating a small wound. Once they have broken the skin, they use a sponge-like mouthparts to soak up the blood.

The bite from a horse fly can be extremely painful for several reasons. Firstly, the cutting action of the bite can cause a sharp, stinging sensation. Plus, horse flies inject an anti-coagulant to prevent the blood from clotting while they are feeding, which can cause the bite site to continue bleeding for a while after the fly has left.

Finger holding a horsefly

Photo Credit: Shutterstock.

This anti-coagulant can also cause an allergic reaction in some people, leading to swelling and itching.

Although horse flies are not known to transmit diseases to humans, their bites can become infected if not cleaned and treated properly. Therefore, if you are bitten by a horse fly, it’s important to clean the bite site with warm water and soap, and apply an over-the-counter antibiotic ointment.

Threats From Horse Flies

Horse flies, despite their seemingly harmless name, pose a significant threat to both humans and animals.

As mentioned previously, their bites can be extremely painful, often resulting in a sharp, burning sensation. This is due to the unique structure of their mouths, which are designed to tear flesh, allowing them to feed on the blood of their host.

Horsefly closeup view on a leaf

Photo Credit: Shutterstock.

In addition to the immediate pain, horse fly bites can also lead to more severe health complications. These flies are known carriers of several diseases, including anthrax and tularemia. While it’s relatively rare for humans to contract these diseases from a horse fly bite, the risk is still present, especially for individuals with weakened immune systems.

Horse flies can also cause significant distress among livestock. Animals such as horses, cows, and sheep are common targets for these flies. The constant biting and harassment can lead to weight loss and decreased milk production in these animals. In severe cases, it can even cause death.

Plus, horse flies can indirectly cause damage to property. The distress caused by their bites can make animals act unpredictably, potentially leading to accidents or damage to farm equipment.

Why Do Horse Flies Bite?

Horse flies are notorious for their painful bites, but why do they bite in the first place? The answer lies in their feeding habits.

Female horse flies, like many other insects, require a blood meal to reproduce. They use their sharp, knife-like mandibles to cut into the skin of their host and feed on the blood that flows out. This feeding process is what we experience as a painful horse fly bite.

Macro on the head of a female horsefly

Photo Credit: Shutterstock.

Males, on the other hand, do not bite. They are primarily nectar feeders and do not require a blood meal for reproduction. It’s important to note that not all horse flies are blood feeders; some species are known to feed on plant sap or other insects.

The biting behavior of horse flies is also influenced by their environment. They are most active in warm, sunny conditions, and their activity tends to peak during the summer months.

They are attracted to movement, shiny surfaces, and carbon dioxide, which is exhaled by potential hosts. This explains why horse flies are commonly found around swimming pools and livestock.

Pictures Of Horse Fly Bites

Horse flies are notorious for their painful bites, and it is essential to be able to identify them to take appropriate measures. This section provides a visual guide to horse fly bites to help you understand what they look like.

Horse fly bites generally appear as red, swollen welts on the skin. They can be quite large and painful due to the unique way in which horse flies feed. Unlike mosquitoes that suck blood, horse flies have scissor-like mandibles that cut into the skin. This results in a more noticeable and painful wound.

Horsefly bite on skin

Photo Credit: Shutterstock.

In the first few hours after a bite, you might notice a small, red bump surrounded by a halo of reddened skin. The area can be tender to touch and might even feel warm.

Over the next few days, the redness can spread, and the site of the bite may become more painful. In some cases, a horse fly bite can cause a large, red, itchy, and swollen welt to form.

It’s important to note that everyone reacts differently to horse fly bites. Some people may experience severe reactions, including hives, fever, or difficulty breathing. If you notice these symptoms, you should seek medical attention immediately.

In our gallery, we have included pictures of horse fly bites at various stages of healing. This can give you an idea of what to expect if you or a loved one is bitten by a horse fly. Remember, these images are a guide and if you’re unsure about a bite or it seems to be causing a severe reaction, always consult a healthcare professional.

How To Protect Yourself Against Horse Flies

Protective measures against horse flies are necessary, especially during their peak activity in the summer months. These insects are not only a nuisance but can also pose a threat to your health due to their painful bites.

Here are some effective strategies to protect yourself against horse flies:

  • Wear Protective Clothing: This is the simplest and most effective way to prevent horse fly bites. Light-colored, loose-fitting clothing is recommended as horse flies are attracted to dark colors and can bite through tight clothes. Also, consider wearing long sleeves and pants when you are in areas known for horse fly activity.
  • Use Insect Repellents: Apply insect repellent on exposed skin and clothing. Look for products that contain DEET, picaridin, or oil of lemon eucalyptus as these are known to be effective against horse flies.
  • Avoid Peak Times and Locations: Horse flies are most active during the warmest parts of the day. If possible, avoid outdoor activities during these times. Also, these insects are common near bodies of water or livestock. Therefore, if you can, try to avoid these areas during horse fly season.
  • Use Traps: There are specially designed traps available in the market that can help reduce the horse fly population in your area. These traps work by mimicking the heat and movement of a large animal, thus attracting horse flies.

Common Types Of Horse Flies

Horse flies are a diverse group of insects, with over 3,000 species found worldwide. They come in various sizes, shapes, and colors but are generally large and robust. Here, we will discuss some of the most common types of horse flies that you may encounter.

  • Striped Horse Fly: The Tabanus lineola, often referred to as the ‘Striped Horse Fly,’ is native to North America. It is primarily a nuisance to cattle and horses, but it can also bite humans when disturbed. It is easily identifiable by its yellow and black striped body and large green eyes.
Selective focus of a striped horse fly on a plant

Striped Horse Fly – Photo Credit: Shutterstock.

  • Yellow Fly: Another common type is the Diachlorus ferrugatus, or the ‘Yellow Fly.’ This species is notorious for its painful bite and is most commonly found in the southeastern United States. The females of this species are blood feeders and can be aggressive when seeking a meal.
Yellow fly on a black surface

Yellow Fly – Photo Credit: Shutterstock.

  • Green Head Horse Fly: The Tabanus nigrovittatus, also known as the ‘Green Head Horse Fly,’ is another species that is widespread in North America. It is particularly known for its metallic green head, which gives it its name. This species is a significant pest to livestock due to its painful bite.
Green Head Horse Fly on a green plant

Green Head Horse Fly – Photo Credit: Shutterstock.

  • Common Horse Fly: The Haematopota pluvialis, or the ‘Common Horse Fly,’ is a species native to Europe. It is smaller than its North American counterparts but is equally as troublesome. It is brown in color with patterned wings and is most active during the summer months.
Common Horse Fly sucking blood on skin

Common Horse Fly – Photo Credit: Shutterstock.

  • Giant Horse Fly: Among the many types of horse flies, the Tabanus sudeticus, or Giant Horse Fly, is one that stands out due to its size and distinctive features. This variety, as the name suggests, is significantly larger than most other horse fly species, often measuring up to 1.25 inches in length.
Giant Horse Fly on white background

Giant Horse Fly – Photo Credit: Shutterstock.

Deer Fly vs. Horse Fly

While both deer flies and horse flies are quite similar, there are some notable differences between these two species.

Size is one of the most noticeable differences. The genus Chrysops, usually known as deer fly, is slightly smaller than Tabanus and has dark markings on the wings. This means horse flies are generally larger, with some species measuring up to 1.25 inches long, while deer flies are usually smaller, often around 1/4 to 1/3 of an inch in length.

Deer fly on a green leaf

Deer Fly – Photo Credit: Shutterstock.

In terms of appearance, horse flies are dark-colored, often gray or black, while deer flies are usually lighter, with a golden or brownish hue. Deer flies are also known for their distinctive patterned wings, which horse flies lack.

Another significant difference is in their biting habits. Both types of flies are known for their painful bites, but deer flies are particularly aggressive. They are more likely to pursue their targets, often biting the head and neck areas. Horse flies, on the other hand, tend to bite the legs or body.

Plus, the horse fly larvae studied by field researchers have been found to feed on midges, crane flies, and even other horse fly larvae. Due to these cannibalistic behaviors, horse fly larvae are usually found living alone. Deer fly larvae, however, usually live in groups.

The life cycles of these two flies also differ. Horse flies lay their eggs in damp soil or plant stems near water bodies, while deer flies lay their eggs on aquatic plants or the water’s surface.

Plus, their preferred habitats vary. Horse flies are often found in rural or woodland areas, especially near water bodies. Deer flies, however, are more common in marshy areas or near bodies of water.

How To Get Rid Of Horse Flies?

Getting rid of horse flies can be a challenging task due to their aggressive nature and their tendency to breed in large numbers.

However, there are several effective strategies you can employ to significantly reduce their presence and protect you and your animals from their annoying and painful bites.

Maintain Your Yard

Maintaining your yard is an effective way to deter horse flies and reduce their population in your surroundings. Horse flies are attracted to wet, marshy areas where they can lay their eggs. If your yard has stagnant water or damp spots, it can become a breeding ground for these pests.

Puddle in the yard

Photo Credit: Shutterstock.

Use Fly Traps

One of the most effective ways to get rid of horse flies is by using fly traps. These traps are designed to attract flies with visual cues and then trap them. There are several types of fly traps available in the market, including sticky traps and baited traps. Sticky traps use a bright color and a sticky substance to attract and capture the flies, while baited traps use a food source to lure the flies into the trap.

Remove Garbage

Garbage, especially food waste, can attract a variety of pests including horse flies. It provides them with a perfect breeding ground, as well as a source of food. Therefore, proper garbage disposal is an essential step in horse fly control.

Ensure that all garbage bins in your home and yard are sealed tightly. This will prevent horse flies from accessing the waste and laying their eggs. Not only does this apply to your general waste bin, but also compost bins and recycling bins.

Clean Up After Pets

Maintaining a clean environment, particularly when it comes to pet waste is also important. Horse flies are attracted to damp, organic matter which often includes pet waste. This serves as a perfect breeding ground for them, enabling them to multiply rapidly.

It’s essential to clean up after your pets regularly to prevent attracting horse flies and other pests. If you have a dog, ensure that you pick up their fecal matter as soon as possible. For those with outdoor cats, consider providing a litter box to control where they do their business.

In addition to this, try to keep your pets’ feeding areas clean. Leftover food can also attract horse flies. Make sure to clean up any uneaten pet food and keep feeding areas as clean as possible.

Burn Candles & Torches

Another effective method of keeping horse flies at bay is burning candles and torches. This method is especially useful during outdoor activities like barbecues, picnics, or while relaxing in your backyard. The smoke and heat from the candles and torches can deter horse flies and other flying insects.

Citronella candle in the yard

Photo Credit: Shutterstock.

Citronella candles are a popular choice, as they release a scent that horse flies and other pests find unattractive. The natural oil found in citronella has proven to be a powerful insect deterrent. Similarly, torches that burn citronella or other insect-repelling oils can create a larger area of protection.

Use Insecticides

Another effective method for controlling horse flies is the use of insecticides. These can be applied to areas where horse flies are known to breed, such as near water sources and in tall grasses. It’s important to follow the instructions on the insecticide label for safe and effective use.

Use Natural Predators

Natural predators such as birds, frogs, toads, bats, and dragonflies can also help control horse fly populations. Encouraging these predators to inhabit your property can help reduce the number of horse flies.

Bird feeder with birds

Photo Credit: Shutterstock.

Manage Breeding Sites

Horse flies breed in wet, marshy areas. By managing these areas and reducing standing water, you can help prevent horse fly larvae from developing. This can involve draining ponds, removing old tires or other items that collect water, and regularly changing the water in bird baths.

Professional Pest Control

If horse flies continue to be a problem, it may be necessary to hire a professional pest control service. These experts have the knowledge and tools to effectively eliminate horse fly infestations and can provide advice on preventing future problems.

Remember, horse flies are more than just a nuisance. They can carry diseases and their bites can cause serious discomfort. Taking steps to control their population can create a safer and more comfortable environment for you and your animals.


Other Fly Guides from Planet Natural:

Mayflies: What Are They and How to Get Rid of Them

How to Get Rid Of Fruit Flies: Simple and Effective Methods

How to Identify and Control Whiteflies Effectively