Black flies, often called “buffalo gnats” due to their humpbacked appearance, are small, dark insects found worldwide, especially near running water. These flies are a common outdoor nuisance, and yes, they do bite.
The Biting Behavior of Black Flies
Only female black flies bite, requiring a blood meal for egg production. Unlike mosquitoes, which pierce the skin, black flies use specialized mouthparts to cut the skin. This cutting action creates a small wound, allowing them to feed from the resulting blood pool.
When a black fly bites, it injects saliva containing anticoagulants and enzymes. These substances prevent blood clotting, facilitate blood flow, and often numb the bite site to extend feeding time. Black flies typically bite exposed skin, favoring areas like the head, neck, ears, and ankles. They can also crawl under clothing to bite.
Identifying and Understanding Black Fly Bites
Black fly bites typically appear as small, red, itchy welts on the skin. A small spot of blood or a tiny puncture wound may be visible at the center of the bite, indicating where the fly cut the skin. The body’s reaction to the fly’s saliva can lead to swelling, redness, and intense itching around the bite area.
The severity of these reactions can vary among individuals. Some experience mild irritation, while others develop more pronounced swelling, which can sometimes be the size of a golf ball. In some cases, multiple bites can lead to “black fly fever,” characterized by headache, nausea, and swollen lymph nodes.
Preventing Black Fly Bites
Protecting oneself from black fly bites involves several strategies, particularly when outdoors during their active season. Wearing appropriate clothing is an effective defense, as black flies do not bite through fabric. Opt for light-colored, loose-fitting long-sleeved shirts, long pants, and a hat, since dark colors can attract them. Tucking shirts into pants and pants into socks helps prevent flies from crawling underneath clothing. A head net provides protection for the face and neck in heavily infested areas.
Using insect repellents on exposed skin is another important preventive measure. Repellents containing DEET or picaridin are generally effective. Reapply repellent as directed to maintain effectiveness, especially during prolonged outdoor activity. Avoiding outdoor activities during peak black fly biting hours (typically 9-11 AM and 4-7 PM) can also reduce exposure. Black flies are most active on humid, cloudy days and just before storms, preferring areas near clean, fast-flowing streams and rivers.
Treating Black Fly Bites
Should you experience a black fly bite, immediate action can help alleviate discomfort and prevent complications. Begin by cleaning the bite area with soap and water to reduce infection risk. Applying a cold compress or ice pack for 10 to 15 minutes can help reduce swelling and pain.
Over-the-counter topical treatments are often effective for managing symptoms. Hydrocortisone cream or calamine lotion can be applied directly to the bites to soothe itching and reduce redness. Oral antihistamines can also be taken to alleviate itching and swelling, particularly for more widespread reactions. Avoid scratching the bites, as this can break the skin and increase the chance of bacterial infection.