From April through October each year, residents of inland Maine endure the annual assault of black flies. These insects are in the order Diptera, along with house flies and mosquities. But, at little more than a 16th of an inch long, they do not resemble either of those insects. Just as there are many species of ordinary flies, there are dozens of species of black flies. And some of those are so tiny they are called no-see-'ums, which is an accurate description.

They are abundant in Maine because all the elements are here to make them thrive: cold, clear running water in which to breed, the right combinations of climate and vegetation, and plenty of large mammals on which to feed.

Each week during the more temperate seasons in Maine a different species or two or three hatches and swarms out in search of blood. For a few days half the human population is being eaten alive and the other half seems to be left alone by the species that is on the loose. A few days later, the just-eaten crowd is sighing in relief and the other half of the population is suffering under the attack of a different species. Just as many other species of insects feed on specific plants and animals, some black flies seem to differentiate between people of different origins - asians and africans and caucasians and so on. Sometimes the little bugs don't seem interested in "biting" but insist on flying into one's ears or eyes instead.

Black flies bite in a manner similar to the rasping sting of a horse fly, rather than the needle prick of a mosquito. They leave behind little purplish dots, which can itch for days afterward. There are commercially-available products to deter them, and most people can find something that works moderately well on an individual basis. Avon's Skin-So-Soft, diluted in water, is still popular, of you can find it. Some Mainers swear by a clove of fresh garlic chopped into aspirin-sized pieces and swallowed like pills. But most of us are merely resigned to the nuisance and suffer the bites of some while swatting away just a few.

After suffering them for a few hours, you really do welcome a swim or a shower to wash away the tiny bodies squished in your hair and the flakes of dried blood where a few of their more aggressive bites drew trickles of blood rather than mere welts.

Eventually, that is after two or three years of grudging tolerance, we find that the bites don't hurt any more, the little purple dots hardly even show up any more, and the sensation of a black fly climbing back up your gullet is more a source of amusement than a disgusting battle between bug and the swallowing reflex.

Visitors who come for brief periods should not expect to simply tough it out. That's admirable, but we hate to have your visit ruined by the results of your stoicism. Wal-Marts all sell green headnets, which provide great relief, and we even resort to those once in a while if we're gardening. A remarkably effective, all-natural herbal product is Lewey's insect repellant, developed and produced in Maine.

Mosquitoes are often more annoying than black flies, depending how close you are to their stagnant breeding pools, but in a way, Maine is defined by its annual black fly infestation. And yet, we don't have most of the nasty creatures that plague our more southerly neighbors. We are free from poisonous snakes and spiders. Killer bees haven't made it this far. Even Japanese beetles and gypsy moths - plant invaders, not human pests - have not effectively made it past the 45th parallel.

We just thought you should be forewarned. We don't hide the fact that we have black flies. We've just grown so used to them that we've pretty much forgotten to think about them until a visitor, suffering for a spell in silence, suddenly demands: "What ARE these horrible little bugs." That's when we are reminded to answer: "Why, that's the Maine State Bird."