When the grip of winter finally becomes weak in central Illinois, sometime around the first week of March, signs of the coming spring have been present for some time, for one who is attuned to slight environmental clues. Less snow, lengthening daytime hours, and warmer temperatures are obvious to even the person most disconnected from nature. Gradually returning bird species, sounding out their spring songs, require a bit more attention to detail, while reawakening plant life can be much more subtle, until the trees leaf out and flowers make their brief appearances. There is a definite optimism in the air as spring gains greater momentum, becoming a rushing torrent of color and sounds by late April. My thoughts fill with plans for outdoor activities, reluctant as I am to miss even one of nature’s spring events. But then the first of the buffalo gnats flies into my eyes and I am undone.
When the buffalo gnats appear, my hopes are dashed, because I know what is coming over the next few weeks: one step outside and a cloud of gnats quickly materializes, spontaneously generated from thin air, over my head with numerous kamikaze-like individuals making forays into my eyes, ears, and mouth, landing on and biting areas of exposed skin. Waving them away only seems to attract more and make them more aggressive. The usual DEET-containing insect repellents have absolutely no effect. And I soon find myself heading for the house, feeling quite beaten, until the sun drops below the horizon and the gnats become inactive.
Buffalo gnats are also called black flies, and while each individual may only be one-fifth of an inch long or less, they attack en masse, by the hundreds it seems. They start showing up during the peak of the songbird migrations in late April or early May, and I have learned to live with them by telling myself that the insectivorous wood warblers, whose flights may take some species from as far as South America to the boreal forests of Canada, must also eat; and what a fine example of an intricately timed natural cycle it is that the migrating warblers seem to peak in numbers at about the same time each year that the buffalo gnats become numerous.
The yearly regularity of the birds and buffalo gnats reminds me that there are many other repeating patterns in nature, such as the spring floods and yearly temperature cycles on Illinois’ rivers. Buffalo gnats are keyed to stream water temperatures and the spring season, so their appearance is actually somewhat predictable, although whether a particular year will be good or bad for gnats is much more difficult to foretell. They inhabit flowing waters, the cleaner and more oxygenated the better; and from egg through their immature or larval stages, buffalo gnats live wholly beneath the water’s surface feeding on algae and other organic material. They continue to emerge from the water in spring as adults until the water temperature reaches about 70 degrees F, which may be around the middle of June, after which the cycle is complete, and the buffalo gnat season is over until the next year. Spawning fish are also keyed to certain water temperatures and also to rising waters during the spring floods. Of course, as with every natural event, there is variability; and some years the spring floods occur a bit later or earlier than average or the water temperature rises slower or faster than average, depending upon weather conditions over the season. Simple physical phenomena such as the tides and the rising sun can be predicted with a great accuracy, while the more complicated ecological events are given to much less certainty; one may make predictions based upon experience of the known ranges of variability for a variety of factors that can influence this or that event, but to say exactly what will happen and precisely when is not possible.
Without a doubt, buffalo gnats are a scourge, and not only from a human-centered point of view; they are capable of killing nestling birds, pets, poultry, and even livestock; people with allergic reactions may have serious complications beyond simply itching and swelling. In fact, in recent years, gnat populations have been so great in parts of west-central Illinois, probably due to higher than usual precipitation and cooler water temperatures remaining longer, that it is likely gnat attacks have caused a long-established great blue heron rookery to be abandoned. In May 2008, nestling bald eagles, with nowhere to escape, were seen to be visibly agitated at Chautauqua National Wildlife Refuge, presumably from unrelenting attacks of buffalo gnats. The situation calls to mind how insulated we humans can be at times within our comfortable environments of our own making from the raw, uncompromising, inconvenient aspects of nature, which, of course, are as much a part of the whole as the human-perceived beauty.
On good days, folks are wont to speak of balance, stability, and harmony in nature, probably because such ideas are attractive and comforting. But are such thoughts realistic? Hordes of any one species, especially one harmful to so many others, does not to me suggest harmony. By cleaning up our pollution from rivers, one might say that we are moving toward a more balanced relationship with the natural world. Fish and mussel communities certainly benefit. But where is the harmony from our perspective when clean, healthy waters result in greater buffalo gnat populations? Though the answer, whatever it may be, is subjective, I have comfort and confidence in one thought: there will eventually again be a year when buffalo gnat populations crash. It is that particular spring I truly look forward to...and that too will not last. Such is the way.
This figure (click on it to enlarge) shows the water level pattern (i.e., hydrograph) of the Illinois River at Havana averaged daily from 1960 to 1993, and actual water temperature readings from 1989 to 1993. In the 1890s, Charles Kofoid of the Illinois Natural History Survey, studied the Illinois River and its floodplain lakes. He documented that the river’s plankton (minute algae and tiny drifting invertebrate organisms called “zooplankton”) peaked, which Kofoid termed a “vernal plankton pulse,” at about the same time that the river reached its highest spring level (the spring flood). We also know that many fish species spawn about this same time, and recently hatched young fish feed extensively on zooplankton. In the fall, fish begin moving toward overwintering areas (e.g., calm backwaters with good oxygen levels) on cue with falling water temperatures and rising water levels. These are only a few of the many other ecological events that can be tied to the river’s hydrograph and temperature.
