Yes, horseflies do bite. These large insects are found globally, often near water or livestock. Unlike many other biting insects, a horsefly bite is distinctly painful and felt immediately. This nuisance is common during outdoor activities, especially in warmer months.
Understanding the Bite
Only female horseflies bite, and they do so to obtain a blood meal necessary for the development of their eggs. This requirement for protein drives their persistent pursuit of warm-blooded hosts, including humans. Male horseflies, in contrast, feed on nectar and pollen from plants and do not bite.
Female horseflies have unique mouthparts designed for cutting, not piercing, the skin. They use sharp, blade-like structures to slice into the skin, creating an open wound. This cutting action, combined with their lack of anesthetic injection, causes immediate and intense pain.
Once the skin is cut, the horsefly uses a sponge-like mouthpart to lap up the pooling blood, often releasing an anticoagulant to prevent clotting. Horseflies are attracted to movement, body heat, and carbon dioxide exhaled by potential hosts, and they visually track large, dark-colored objects.
Dealing with a Bite
A horsefly bite typically results in immediate, sharp pain, followed by localized symptoms like redness, swelling, and itching. A raised welt or minor bleeding at the bite site is also common. The affected area can become tender.
To manage a horsefly bite, clean the area thoroughly with soap and warm water to prevent infection. Applying a cold compress or ice pack can reduce pain and swelling. Over-the-counter remedies like oral antihistamines alleviate itching, while hydrocortisone cream may reduce inflammation and discomfort.
Avoid scratching the bite, as this can introduce bacteria and lead to secondary infection. Seek medical attention if signs of infection develop, such as increased redness, warmth, pus, or worsening pain. Immediate medical help is also necessary for severe allergic reactions, including dizziness, wheezing, difficulty breathing, or swelling of the face, lips, or throat.
Avoiding Bites
Preventing horsefly bites involves several strategies. Wearing long-sleeved shirts and trousers covers exposed skin, though horseflies can sometimes bite through thinner fabrics. Choosing light-colored clothing is beneficial, as these insects are attracted to dark colors. Loose-fitting garments are also recommended, creating a barrier horseflies may find harder to penetrate.
Using insect repellents containing active ingredients like DEET or picaridin offers protection. Permethrin-treated clothing can deter horseflies, but should not be applied directly to the skin. Avoiding prevalent areas like marshes, dense vegetation, and livestock locations reduces bite risk. Horseflies are most active during warm, sunny conditions and peak times like dawn and dusk; planning outdoor activities to avoid these periods can be helpful.