Black flies surge in Maine's clean rivers

Citing environment's gain, state declines to curb the biting bugs

MILLINOCKET, Maine - Mainers call the black fly the state bird.

Residents and tourists have long steeled themselves against the flies' annual warm-weather onslaught, sometimes duct-taping pant legs and wearing screened hoods to keep the deceptively small bugs from delivering bloody bites or crawling into seemingly every body crevice.

But there are now more black flies in more places in Maine, and the reason may be surprising: It's the success of the environmental movement.

Many species of the gnat-sized insects are sticklers for cleanliness. When Maine's rivers were filled with contaminants from paper mills and other industries, only the hardiest black flies laid eggs in them. Now, rivers and streams are progressively cleaner, providing ideal breeding grounds for the annoying pests.

It's an unintended barometer of good ecological health, but Maine officials are adamant they will not mess with nature in any way to provide relief.

"They can be so thick you breathe them in and they get stuck in your throat. They even get under your eyelids," said Julia Brilliott, an Eastport resident who showed off four lumpy red welts on the back of her neck after climbing Mount Katahdin in Baxter State Park last week.

For the uninitiated, black flies are blood-sucking insects with a menacing reputation worthy of a late-night science fiction movie. Not all bite humans - some feed on other mammals and birds - but those that do are relentless daytime feeders. Even the nonbiting flies are often despised because they emerge by the millions in warm months and, lured by the carbon dioxide we exhale, swarm around people.

Each species of black fly has its own ecological niche. In New England, they are partial to the White Mountains, Berkshires, and North Woods. Some in Maine are fierce biters that tend to emerge around Mother's Day and disappear by about Father's Day. Others, some that bite humans and some that don't, will emerge later in the season.

Some states, such as Pennsylvania, heavily control black flies. Officials there spend about $6 million a year treating 47 rivers and streams with a bacteria whose naturally occurring toxin kills black fly and mosquito larvae. Pennsylvania officials say the bacteria, called Bti, are not harmful to humans, mammals, birds, fish, plants, and most aquatic organisms.

Maine officials say they won't use it, however. The rivers were polluted enough in the past, and officials refuse to put anything else in them unless it's to solve a human health crisis. They say trout and birds feed on black flies, so killing fly larvae could have ripple effects on wildlife. And Bti kill other fly species that are part of a healthy ecosystem.

"We do not favor anything that is toxic to one organism because we often find out down the road they are toxic to others," said David Littell, commissioner of the Maine Department of Environmental Protection.

Black flies are found the world over and scientists have documented more than 2,000 species living from the North Pole to just north of Antarctica. In Africa, the insects can transmit a parasite that causes human blindness and in the United States, the flies have caused disease outbreaks in birds and regularly pester livestock. In New England, the bugs deliver only painful bites, although some people are allergic to them.

"They are particularly troubling for animals, but for humans they are mostly a nuisance," said Peter H. Adler, an entomology professor at Clemson University who is a black fly specialist. He recently wrote a book about the 255 species in North America. "If you have seen one black fly, you have not seen them all."

Unlike mosquitoes, which breed in stagnant pools, black flies like clear running water. The adult female typically mates with males in midair before seeking a blood meal to nourish eggs. The female then deposits the eggs in flowing water, where they hatch into larvae. But the running water must be nearly pristine: Black flies are incredibly sensitive to pollution.

The flies have been a pesky nuisance for centuries in New England. Some of the earliest attempts at control took place in New Hampshire in the early 1900s when officials poured diesel oil and kerosene into rivers, according to Adler. Chemical insecticides were later used, but paper mills, raw sewage, and other pollution probably did a better job at knocking the fly down: By the middle of the last century, black fly populations were reduced in polluted Maine rivers and streams.

The federal Clean Water Act, which passed in 1972 and required the cleaning of waterways, helped bring the black fly back, according to entomologists. Today, dozens of species in Maine are thriving in places they were rarely seen in the past, such as around the Penobscot and Kennebec rivers. Scientists say there are black flies in places they haven't been before. And in places where they were, there are even more.

"We may still have the same number of species, but before, their distribution was limited," said Jim Dill, pest management specialist with the University of Maine Cooperative Extension. "People tell us they are more abundant or they say they are nastier biters."

So how to protect yourself? Wear light-colored clothing. While it may not look fashionable, tuck pant legs into socks or boots and wear tight-fitting, long-sleeved shirts because the flies often crawl into snug regions of the body to feed. Insect repellents also work.

Laurie Cormier, owner of the Big Moose Inn, Cabins and Campgrounds outside Millinocket, says the flies are simply a part of Maine - just like moose, bear, and fish. Still, construction workers at her rustic inn had to wear headgear with netting recently to protect themselves outdoors, which made them look like "they were from another planet," she said.

To be sure, there are some people who are downright happy about the fly population increase.

Members of the Maine Blackfly Breeder's Association in Machias are even taking credit for it. Organizers of the tongue-in-cheek organization, whose motto is "We breed 'em you feed 'em," say they are working to breed black flies with fireflies so the flies can be active at night. The group holds an annual convention and raises money for local charities.

"We are ecstatic," said Marilyn Dowling, who calls herself the director of research and development for the association. She and Holly Garner-Jackson, the marketing director, said people have a choice: polluted rivers and no black flies, or clean rivers and black flies. People "should roll up their sleeves to feed the little darlings," Dowling said. "They are defenders of the wilderness."

Beth Daley can be reached at bdaley@globe.com. For more information on the Web, visit mainenature.org /blackfly/blackflyinfo.html and maineblackfly.org.