Black flies, Buffalo gnats or Turkey gnats are true flies – not a bee, wasp or ant. They are very small – one to five millimeters long – and usually black to gray in color. Black flies tend to bite where clothing fits tightly against the body. Therefore, just above socks, around the neck, at the brim line under a hat or around the belt line at the waist are favored feeding sites. The female black fly must have a blood meal in order to mature and produce viable eggs. Biting can occur at any time during the day and into the night. The black fly female has mouthparts that are like tiny knife blades. With these she cuts into your skin to expose blood capillaries. While she is cutting, she is also injecting saliva into the wound. The saliva does two things – it anesthetizes the cut so you cannot feel it happening, and it contains an anticoagulant so the blood keeps flowing. However, once the anesthesia wears off, the foreign proteins left behind can cause an intense itching, swelling and reddening of tissues. Sensitive persons may get sick with a headache, nausea, fever, and inflammation of lymph nodes caused by black fly bites. Severe symptoms are known as black fly fever.
The young of most black flies are aquatic larva which live in streams, lakes or vernal pools. The adults usually emerge in the spring, are active (bite) for a few weeks and then disappear. When gardening wear long-sleeved shirts and long pants tucked inside your socks. Cover any exposed skin with insect repellent, especially around the head under your hat and around the neck at the collar. Applying insect repellent to your clothing around your wrists, ankles and waist line is also recommended.