Black Flies

Black Flies Why Are They a Problem?

Some species that seldom bite can be very annoying because they tend to fly around the head and the face. Unlike the mosquito, black flies bite only during the day, which can make them a nuisance to humans. Black flies bite exposed areas and they will also crawl through small openings in clothing, so keep yourself covered! Although the actual bite may not be painful, swelling may occur later on and the area may remain sore and itchy for several days or even longer.

Black Fly Biology

Like the mosquito, the black fly also has four life stages: egg, larva, pupa and adult. The first three black fly stages develop only in fast-flowing water. In the springtime, every spring and river is a potential breeding place for black flies. Depending on the species and environment, the length of time spent by a black fly in the water stages may be as short as two weeks or as long as several months. The adult emerges from the pupal skin, rises to the water surface and takes flight almost immediately. Adult black flies are small, stout-bodied, hump-backed flies with short, broad wings and short legs.

Most of us think of black flies as one of the most annoying of the biting insects. However, depending on the geographical location, black flies may only be a problem for three or four weeks of every year — and some species of black flies don’t even bite! The lifespan of the adult black fly ranges from a few days to several weeks. For some species a second generation of black flies may develop in the early fall. The female starts looking for her blood meal approximately two weeks after emerging.

How to Avoid Black Flies

  • Wear protective clothing (e.g. long sleeves and pants).
  • Wear light colours such as; orange, yellow, light green, and blue. Light colours are less attractive than dark colours.
  • Black flies are most active in the morning, late afternoon and on warm, overcast days.
  • Black flies are most bothersome in the bush rather than open country.

Recommended Treatment

You can protect yourself and your family from black fly bites by wearing an OFF!® repellent.