San Gabriel Valley residents are facing an unusual wave of tiny eye‑biting black flies that swarm around faces and necks, leaving painful bites, especially near the eyes.
As reported by the L.A. Times officials say activity is unusually high right now in foothill towns like Altadena, Azusa, Glendora, and Monrovia. In order to control the fly surge, they’re treating river and stream breeding sites, but relief could take weeks.
What are the “eye-biting flies”?
Black flies (also called buffalo gnats) are tiny dark flies that breed in flowing water like creeks and rivers. Females lay hundreds of eggs on or near running water, and larvae cling to rocks until they mature.
Warmer temperatures and increased water flow, create ideal conditions for a boom in their numbers. These flies are just a few millimeters long, and the females bite to get the blood needed to produce eggs.
They fly in large numbers and long distances and target thin skin around the head, eyes, and neck, using scissor‑like mouthparts to cut the skin before feeding. Though their bites are painful and itchy, black flies are not deadly or disease-carrying, just very bothersome.
How to protect yourself from eye-biting flies
Biting flies are drawn to dark colors like blue, black, dark red, and dark green, with blue being the strongest attractant. To stay less noticeable outdoors, wear light-colored clothing.
Still, the San Gabriel Valley Mosquito and Vector Control District advises residents to take these measures to avoid bites.
- Wear a head net, which can be found at outdoor or gardening stores.
- Apply DEET-containing insect repellent on exposed skin.
- Stick to open, sunny areas and avoid lowlands or densely vegetated spots.
- Stay indoors during dawn and dusk when flies are most active.
- Cover exposed skin with long-sleeved shirts, long pants, socks, and hats.
If you get bitten by black flies, Very Well Health recommends following these instructions to fight the discomfort and prevent complications:
- Clean and disinfect the bite to lower the risk of infection.
- Apply a topical anti-itch or pain-relief product, like cortisone cream or spray.
- Use a cool compress for 10–15 minutes at a time, wrap ice in a cloth, or use a chilled pack, but never place ice directly on your skin.
- Take an over-the-counter pain reliever, such as ibuprofen (Advil or Motrin), if needed.
- Avoid scratching, since it can damage the skin and increase the chance of infection.
When in doubt, or if a bite doesn’t improve, reach out to your doctor for guidance.
