Black flies are a common warm-weather nuisance across Michigan. These small, biting insects can significantly impact activities like hiking, fishing, and camping during certain times of the year. Understanding their seasonal presence and preferred environments can help outdoor enthusiasts better prepare for and mitigate their impact.
Understanding Black Fly Season in Michigan
Black fly season in Michigan typically begins in late spring and can extend into early summer, with peak activity generally occurring from mid-May to mid-June. However, the exact timing and duration can vary based on regional differences and prevailing weather conditions. For instance, black flies may emerge earlier in southern Michigan compared to the Upper Peninsula, where cooler temperatures can delay their appearance until late April, potentially lasting until early September.
Michigan is home to over 65 species of black flies, and their diverse life cycles contribute to the extended season. Their emergence is closely tied to water temperature, with eggs hatching rapidly following snowmelt and increasing water temperatures in late February in some areas. Female black flies require a blood meal for egg development, after which they lay 200 to 500 eggs in moving water.
Where Black Flies Are Most Prevalent
Black flies are most commonly found near clean, well-oxygenated flowing water sources like rivers, streams, and creeks, as these are essential for their larval development. This strong association with aquatic habitats means they are particularly abundant in Michigan’s northern regions, including the Upper Peninsula, which boasts numerous such waterways.
The improving water quality in some southern Michigan rivers and streams has also led to a noticeable increase in black fly numbers in those areas. These insects tend to swarm, often targeting the face and around the ears. They are also known to emerge in the Western Upper Peninsula and along the Lake Superior shoreline before other areas.
Preventing Black Fly Bites
Protecting oneself from black fly bites involves clothing choices and the use of repellents. Wearing light-colored clothing is advisable, as black flies are attracted to darker hues. Long-sleeved shirts and long pants can offer protection because black flies generally cannot bite through clothing. Tucking pant legs into socks and shirts into pants can further prevent flies from crawling underneath clothing.
Head nets are highly effective for protecting the face, ears, nose, and mouth, especially in areas with dense swarms. While black flies are active during the day, they are often most aggressive during morning and early evening hours, so avoiding outdoor activities during these times can help. Insect repellents containing DEET or picaridin can offer some protection, though their effectiveness can vary against black flies.
Treating Black Fly Bites
Black fly bites often result in small, itchy, and sometimes bleeding welts, which can swell and remain itchy for weeks. Immediately cleaning the bite area with soap and water can help reduce the risk of infection. Applying a cold compress or ice pack can reduce swelling and discomfort.
Over-the-counter remedies such as hydrocortisone cream, calamine lotion, or oral antihistamines can alleviate itching and swelling. It is important to avoid scratching the bites, as this can worsen the irritation and lead to secondary infections. While black fly bites are not typically dangerous and North American black flies do not transmit diseases to humans, seeking medical attention is advisable if signs of infection appear, such as increased pain, redness, warmth, or pus, or if an allergic reaction occurs, indicated by severe swelling, difficulty breathing, or dizziness.