Greenheads are a type of biting fly found in coastal regions. These insects are a common nuisance for beachgoers during warmer months. They belong to the Tabanidae family, commonly known as horseflies, and are widely distributed along the Atlantic coast. Understanding their characteristics and behaviors can help minimize their impact on outdoor activities.
Identifying Greenheads
Greenhead flies have distinct physical characteristics. They are typically about half an inch long, larger than a common housefly but often smaller than other horsefly species. Their most notable feature is their large, iridescent compound eyes, which appear as a striking dark green.
These flies have a flat head, a light brown body, and clear wings. Distinguishing them from other insects involves observing their size and prominent green eyes.
Why Greenheads Are Found at the Beach
Greenhead flies are found in coastal environments due to their habitat needs. They breed in salt marshes and tidal flats, where their larvae develop in moist, muddy conditions. These wetlands provide an ideal environment for their reproductive cycle, as females lay egg masses on marsh grass. After hatching, the worm-like larvae burrow into the marsh, feeding on organic matter and smaller invertebrates for one to two years before pupating.
Adult greenheads emerge in late spring, with populations peaking from late June through August, often in July. Female greenhead flies require a blood meal to produce additional egg masses. They are active during daylight hours, particularly during the hottest part of the day, and can fly for miles from their marsh breeding grounds in search of blood. They are attracted to carbon dioxide and other chemicals emitted by humans and animals, as well as by movement and dark objects.
Preventing Bites and Finding Relief
Preventing greenhead bites involves several measures. Wearing light-colored clothing makes individuals less attractive, as these flies prefer dark objects. Avoiding the beach during peak activity times, often the hottest part of the day from late morning to dusk, can also reduce encounters. Some insect repellents containing DEET or picaridin may offer protection, though their effectiveness against greenheads varies. Staying close to the water’s edge, where a breeze may deter them, can also be beneficial.
If bitten, immediate relief can help manage symptoms. Greenhead bites cause an instant, sharp burning sensation, followed by intense itching and swelling. Applying an ice pack or cold compress to the affected area helps reduce pain, itching, and swelling. Over-the-counter anti-itch creams, such as hydrocortisone, and oral antihistamines can also alleviate discomfort. Avoid scratching the bite, as this can break the skin and increase the risk of infection; most bites are not serious and typically resolve within a few days.