Flies with iridescent green bodies or striking green eyes are a common sight, leading many to wonder if these “green flies” pose a biting threat. The term “green fly” often broadly refers to various species, some harmless and others known for their painful bites. This article clarifies which green-colored flies bite and offers advice on how to identify and prevent their bites.
Do Green Flies Bite
Many flies commonly referred to as “green flies,” such as green bottle flies, generally do not bite humans. These flies are often found near decaying organic matter and posing health concerns by potentially carrying bacteria to food. However, the term “green fly” also refers to certain species within the Tabanidae family, like some horse flies and deer flies, which possess prominent, often iridescent green or blue eyes.
Female horse flies and deer flies bite humans and other mammals. They require a blood meal to produce eggs, using specialized mouthparts to cut the skin and then lap up the blood. Male flies, in contrast, primarily feed on nectar and are not equipped for biting.
Recognizing Biting Flies
Horse flies and deer flies, both members of the Tabanidae family, are often perceived as “green” and are known for biting. Horse flies are generally larger, ranging from 0.25 to 1.25 inches long, with robust bodies and large, often iridescent green or purple banded eyes. Some species, like the green horse fly (Chlorotabanus crepuscularis), have entirely green bodies. They are strong, fast fliers, often found near streams, marshes, and wooded areas.
Deer flies are smaller than horse flies, typically measuring around 0.25 to 0.75 inches, with yellowish or greenish bodies and distinctive dark wing patterns. Their eyes are also brightly colored and iridescent. Deer flies are abundant in damp, wooded, or wetland environments, such as marshes and pond edges. Both are attracted to movement, dark objects, and carbon dioxide, which helps them locate hosts.
What to Do About Bites
Bites from horse flies and deer flies are often immediately painful, sometimes described as a sharp sting. The bite occurs when the fly uses its blade-like mouthparts to cut into the skin, leading to a small wound from which blood flows. Common symptoms include localized redness, swelling, and itching, with a raised welt forming at the bite site.
To treat a bite, promptly clean the area with soap and water to prevent infection. Applying a cold compress or ice pack for 10-15 minutes can help reduce pain and swelling. Over-the-counter remedies such as hydrocortisone cream or calamine lotion can alleviate itching and inflammation. Oral antihistamines can also help manage itching and swelling. Seek medical attention if signs of infection develop, such as pus or increased warmth, or if you experience a severe allergic reaction like wheezing, dizziness, or difficulty breathing.
Avoiding Green Fly Bites
Preventing bites from these flies involves several strategies, especially when outdoors in their habitats. Wearing protective clothing, such as long-sleeved shirts, long pants, and a wide-brimmed hat, can cover exposed skin and reduce biting opportunities. Light-colored clothing is often less attractive to these flies than dark colors.
Using insect repellents containing active ingredients like DEET or picaridin can offer some protection, though deer flies can be resistant to certain sprays. Applying permethrin-based repellents to clothing, but not directly to skin, can also be effective. Avoiding outdoor activities during peak fly activity, often during daytime hours in warm, humid conditions, particularly near wetlands or wooded areas, can also minimize exposure.