The Blackfly Connection

These tiny biting insects are growing in number as waterways clean up

  • Roger Di Silvestro
  • Oct 01, 2008
HAVE YOU EVER been to Maine between Mother’s Day and Father’s Day? If so, you may have stepped outdoors to find yourself swarmed by countless gnatlike blackflies that had you slapping frantically at the air around your head (a form of behavior sometimes known as “the angler’s salute”). Frantically because some blackflies bite—with painful and itchy results—while others that don’t can lodge in your eyes, nose, throat and ears. They make any visit to Maine during blackfly season memorable, though not for the reasons that a board of tourism might wish.

Well, Mainiacs, brace yourselves, because the situation is reportedly going to get worse. According to biologists who study blackflies—and who recognize more than 2,000 blackfly species found from the North Pole almost to Antarctica—the flies are showing up in places where they have not previously been recorded, and they are becoming more numerous in areas where they are well known.

Are the biologists blaming global warming and the fossil fuel industry for these population booms? No. The culprits, say state officials, are environmentalists, the very environmentalists who have cleaned up waterways in Maine and other New England states.

It seems that black flies, which lay their eggs in water, like a clean environment. In the middle of the last century, when local rivers and streams were suffering from a variety of historic ills—pollution from paper mills and raw sewage, for example, and the pouring of diesel fuel and kerosene directly into streams to discourage flies—the insects declined. Then came the federal Clean Water Act and other measures designed to clean up polluted rivers and streams. Bingo—the flies bounced back. Highly sensitive to pollution, the insects are a sign of ecological health (no one ever said that a clean environment would be easy to live in).

Some states still try to control the flies. Pennsylvania, for example, treats some rivers ands streams with a bacterium that kills blackfly larvae. But Maine is having none of it. After cleaning up waterways, state officials are in no hurry to start putting artificial additives back into them. As David Littell, a commissioner of the Maine Department of Environmental Protection, told a Boston Globe reporter, “We do not favor anything that is toxic to one organism, because we often find out down the road they are toxic to others.” Even if they aren’t, eliminating the flies could have harmful effects on the fish and birds that feed on the insects.

So if you find yourself in Maine, or other blackfly habitat, during fly season, swatting at clouds of dive bombers circling your head, just remember: Every one of those tiny marauders is a sign of a cleaner, healthier environment. Then put on light clothing, a head net, tuck your pants into your socks, and maybe next time, plan to come at a different time of year.

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