Black Fly

photo by Fyn Kynd CC BY

Black Fly are one of the hazards of heading into northern forests and along cold running water as they bite. Most abundant from the middle of May to late June, they can be found throughout northern Canada and the northern United States. Only the females bite, and they use the blood for egg development.

Black Fly lay their eggs in water where the larvae attach themselves to rocks or plants. The adults float upwards in a bubble of air and are ready to fly as soon as they emerge from the water.

Black Fly are small (less than 1/4 in long) with a humpbacked, gnat-like appearance and clear, broad wings. Not all are black. Some are yellowish orange or brownish gray.

Did you know? Black Fly are valuable pollinators of wild Blueberry and an important fish food.

See Also: Horse Fly, House Fly