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Public Radio's Environmental News Magazine (follow us on Google News)

The Dreaded Black Fly

Air Date: Week of

They’re bloodthirsty. They’re vicious. They are the tiny black flies that infest northern New England and torment tourists and natives alike for the weeks of early summer. Commentator Sy Montegomery delves into what makes black flies the eternal foe of New Englanders.


CURWOOD: If you don't live in the northeastern part of North America, then you may well have been spared the black fly. So you might then wonder at the bizarre behavior that some residents of the region exhibit this time of year. Commentator Sy Montgomery explains.

MONTGOMERY: Some of us call it the New Hampshire salute. It looks like we're always trying to hail a cab. Actually, we're just flailing at the clouds of black flies around our faces. Some brave souls try to deter the bugs by wearing mesh-covered suits and hats called bug bafflers, which makes you look like an alien in an ill-fitting spacesuit. The insect's worm-like larvae live only in clean, fast-flowing streams and rivers, the very waterways that draw tourists to northern villages, mountain resorts, and fishing lodges. What the travel brochures don't report is that more than 40 species of black flies begin to emerge from these scenic waterways in late April, reaching a silent crescendo in late May or early June, and lasting into the summer. Just how bad are they? So bad that some historians think black flies might have caused the spring migrations of many tribes of Native Americans. And we're not the only continent afflicted. In Eastern Europe in 1923, the flies were so vicious that 20,000 horses, cattle, sheep, and goats actually died from their attacks. If you look at a black fly under a microscope, you can see this is one tough cookie. Only the females bite. Like the mosquito she needs blood to lay her eggs. First, she hovers. Then she alights, pats your skin with her front legs, where she has sensors to help her pick the right spot, and then the fly clamps onto you with a set of teeth in the front of her mouth. Two rows of teeth behind those saw through your skin to create a little pool of blood. As the insect sucks that up, she lowers another set of mouth parts to the wound to drool into it. That's why black fly bites bleed so much. Their drool contains a complex cocktail of chemicals that prevent blood from clotting. Ready for more bad news? They're getting worse. Used to be they're only out for a month or so in the spring, but now in some areas they're around all summer long. The reason? We've cleaned up our rivers. Pollution and industry drove many species of black flies away. Cleaner rivers mean better habitat for more species of black flies to reclaim their former range. And alas, I found nothing that really repels them. So I'm destined to a lifetime of outdoor summer weddings with my face swelled up like Quasimodo. There is, though, one feature of their behavior I can appreciate. At least they have the courtesy to stand still while you squash them. And in this, there is great heartlifting joy.

(Music up and under)

CURWOOD: Living on Earth commentator Sy Montgomery is the author of Nature's Everyday Mysteries.



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