Horse flies are large insects known for their painful bites. Their presence is often marked by a persistent buzzing and a sudden, sharp pain. These insects are a common nuisance for humans and animals due to the biting behavior of the females.
Understanding Horse Fly Behavior
Only female horse flies bite, needing a blood meal to produce eggs. Male horse flies feed on nectar and pollen. Female horse flies have blade-like mouthparts that cut into the skin, creating a wound to feed on blood. This method is distinct from a mosquito’s piercing bite, causing immediate and noticeable pain.
Horse flies thrive in warm, humid environments near water sources like streams, wetlands, and ponds, which are ideal for larval development. They are most active during daylight hours, particularly on hot, sunny, and windless summer days, with peak activity often occurring around midday. These insects have keen eyesight and are attracted to large, dark, moving objects, heat, carbon dioxide, and sweat, which helps them locate potential hosts.
Personal Prevention Methods
Personal protective measures can minimize horse fly bites. Applying insect repellents containing active ingredients such as DEET, picaridin, or oil of lemon eucalyptus (PMD) can deter these biting insects. Apply these repellents evenly to exposed skin according to product instructions for effective protection.
Wearing light-colored, loose-fitting, long-sleeved shirts and long pants also helps prevent bites. This clothing reduces exposed skin and makes you less visible to horse flies, which are attracted to dark colors. Avoid strong scents like perfumes or heavily fragranced sunscreens in horse fly-prone areas, as they may attract insects. If possible, schedule outdoor activities during cooler parts of the day or when wind speeds are higher, as horse fly activity tends to decrease in such conditions.
Environmental Control Strategies
Environmental strategies can help reduce horse fly populations. Specialized black spherical traps mimic a host by absorbing sunlight and radiating heat, attracting female horse flies. When they land on the heated ball and fail to obtain a blood meal, they fly upwards into a collection bin, becoming trapped.
Habitat modification can also reduce horse fly numbers. Since horse flies lay eggs in moist soil or near water, managing standing water and ensuring good drainage around homes and stables reduces breeding grounds. Clearing dense brush and maintaining tidy areas eliminates resting spots for adult flies. Installing screens on windows and doors prevents horse flies from entering indoor spaces. For livestock, using fly sheets or applying insect-repellent sprays directly to animals protects them and indirectly reduces horse fly presence.