As we’re entering black fly season – approximately between mother’s day and father’s day in northern New England – consider reasons to appreciate them.
-Black flies are a sign of good water quality. Female black flies lay their eggs in running water. When the eggs hatch, the larvae, which look like wormy bowling pins because of their bulbous rear ends, attach themselves to submerged stones and branches and filter the bacteria, algae, and organic matter with hairy fan-like mouth parts. Most black fly species will not tolerate pollution.
-Black flies are an important part of the food web. Larvae and adults serve as food for fish (including trout), birds (notably nesting northern ducks), insects, and bats.
-Of the 40 species of black flies in Vermont, only 4 or 5 bite humans, most species feed on birds or other animals. Only female flies seek to bite warm-blooded animals with their serrated, scissor-like jaws. They need a blood meal to lay viable eggs. Males do not even have mouth parts that can bite; they only sip nectar.
To protect yourself from black fly bites, wear light-colored clothing that does not have buttons (the flies can crawl in through the spaces between the buttons), tuck your shirt into your pants, wear a second layer, and perhaps a head net. Black flies are most active during the day—especially on cloudy, still, humid days—and do not like to go indoors.
Celebrate black flies at the annual Blackfly Festival in Adamant, Vermont on June 6th!
