Horse flies are a type of biting fly that is larger than most fly species. They belong to the Tabanidae family and are often found near water, farms, and wooded areas. Horse flies are similar in appearance to house flies but are larger and have sharp mouthparts that cut the skin to suck blood. Their bites can be itchy and may sometimes cause infections.
Horse flies are biting flies often found near water, farms, and wooded areas. Some species grow up to one inch long and are usually black or dark brown, with large green or black eyes and sometimes patterned wings. Males have touching eyes, while females’ eyes are separated. Their bites can be very painful because they use sharp, scissor-like mouthparts to cut the skin. If a bite becomes very swollen, painful, or red, seek medical advice.
Horse flies thrive in warm, damp environments and become most noticeable during the warmer months. Understanding where they live, what they eat, how they develop, and how they behave can help explain why they are such persistent biting pests around people, livestock, and rural properties.
They are especially common near standing water or wet ground, where their young can develop, and around livestock or other animals that provide easy access to blood meals. These conditions make farms, stables, and wooded rural areas ideal habitats for horse flies.
Male horse flies feed on nectar and plant juices. Female horse flies, however, need blood to produce eggs, which is why they bite animals and people. They are attracted to movement, body heat, and carbon dioxide, which helps them find their targets. Their sharp mouthparts allow them to slice the skin and lap up blood.
The life cycle of horse flies can last from a few weeks to over a year, depending on the environment. Mating is initiated in the air and completed on the ground, where the females deposit an egg mass that sometimes has a shiny or chalky secretion, which aids in water protection. Females lay eggs in masses ranging from 100 to 1000 on vertical surfaces over water or wet ground, which is ideal for larval development. The eggs hatch in five to seven days.
After hatching, the larvae drop into water or damp soil, where they feed on decaying matter. They overwinter in the larval stage and pupate during the spring and early summer. Once they become pupae in dry soil, they transform into adult flies. The adult life cycle lasts 30 to 60 days.
Horse flies are most active during the warmer months, especially in late spring and summer. During this time, female horse flies search for blood meals to reproduce. Rainy weather creates more breeding spots, increasing their numbers.
They are persistent biters and will keep trying to feed if they detect a nearby host. Their painful bites come from scissor-like mouthparts that slash the skin as they feed.
Reducing horse fly populations requires removing breeding sites, using traps, and protecting animals. Read on to learn more about the signs of infestations and how we can help manage horse fly populations.
Horse flies can be a big problem, especially in areas with animals or water. One of the first signs of an infestation is seeing large flies buzzing around people, livestock, or pets. These flies are most active during the day and can leave painful, bleeding bites.
Their bites can cause redness, swelling, and irritation, and some people and animals may have allergic reactions, which make symptoms worse. If a bite becomes very swollen, infected, or doesn’t heal, it’s important to see a doctor to avoid serious issues.
You may also notice more horse flies near water, such as ponds, marshes, or damp soil. These are areas where they lay their eggs, so their numbers can grow quickly. Barns, stables, and pastures can also attract them.
Spotting the signs early can help you take action before the problem escalates.
These large, biting horse flies are attracted to animals and water. Remove breeding areas like standing water and keep stables clean. Protect animals by using fly masks or sheets and keeping them inside during the day when horse flies are most active.
Horse flies are also attracted to flowering plants, so removing them around barns or pastures can help keep them away.
For help controlling horse flies, contact our fly control experts.
Horse fly bites can be painful and cause swelling. Wash the area with soap and water and use ice to reduce swelling. If you have an allergic reaction, seek medical help.
Female horse flies need blood to reproduce, making them very determined to find a host. They are attracted to movement, body heat, and carbon dioxide.
Horse flies are common in warm, humid places like wetlands, forests, and farms. They are most active in late spring and summer.
Horse flies are drawn to body heat, sweat, dark clothing, and carbon dioxide. Scented products may also attract them.
You may see more horse flies if there are water sources, livestock, or humid conditions nearby that support their breeding.
Horse flies don’t spread diseases like mosquitoes, but their bites can hurt, swell, and sometimes get infected or cause allergic reactions. If you have severe swelling, signs of infection, or an allergic reaction, seek medical help right away.
Learn more about other common flies found in the US, including drain flies, crane flies, house flies, and autumn flies, and how to identify them.
Drain flies are small, dark-colored insects often found near sinks, drains, and sewage systems.
Autumn flies, known for clustering around windows in cooler months, invade homes seeking warmth.
Crane flies are easily identified by their long, delicate legs and slender bodies.
Drain flies are small, dark-colored insects often found near sinks, drains, and sewage systems.