The River Landing

Buffalo Gnats: The Scourge of Clean, Flowing Waters

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.

An Illinois River Bluff Hike and Turning 52

I rolled out of bed the morning of my 52^nd birthday feeling the usual familiar pains in my left foot and lower backside. But I truly felt no older than I had felt the year before, and actually felt quite younger than those first shocking moments of turning 50 – which really was not so bad after all. Folks decades older, I am sure, would think of such thoughts as ridiculous folly. For my birthday gift, I chose a hike with my wife Julie on the Illinois River bluffs at Forest Park South Nature Preserve.

As I dressed, in my mind’s eye I contrasted the view from the back door of our Mason County home, a rather flat to gently rolling countryside, with the rugged bluffs at Peoria that abruptly rise some 200 feet above the river; the bluffs more resemble foothills of the Missouri Ozarks than central Illinois’ agricultural landscape. From Havana, we followed the river bluffs in a northeasterly direction just beyond Peoria to the Forest Park Nature Center. Then without delay, we began our hike to the bluff tops; it was a steep hike at times, and I had to favor my right knee, for a moment feeling older than my years, lest I cause aggravation of an old injury. Just as we entered the woods, I heard a white-breasted nuthatch, tufted titmouse, and black-capped chick-a-dee, and I knew that we were in the midst of a mixed-species flock of birds foraging their way through the forest, looking for insects in crevices of tree bark or snapping up an occasional seed or berry. In a moment, there was a brown creeper and downy woodpecker, all part of the diffuse flock.

Part way to the top of the bluff we sat and rested upon a large boulder, listening and watching the birds moving onward. The boulder was certainly a hard seat, but it reminded me that the river bluffs were actually formed thousands of years ago at the edge of a great glacier that grinded across the land from the top of the world, that reached all the way around the earth’s northern hemisphere to Siberia. The glacier ended at Peoria where it melted at the same rate as it moved forward for thousands of years, dropping rocks, boulders, gravel, and sand onto a terminal moraine like a giant conveyor belt. The boulder we rested on, in fact, was once probably in Canada.

After a few minutes, we continued our hike to the bluff top. Once reaching the ridge, the trail was more level and the hike was easier. I recalled from a previous hike on this trail encountering an elderly gentleman walking with a cane, and I thought that if I could do the same in a few decades, I would feel satisfied, to say nothing of feeling extremely fortunate.

We enjoyed walking through the mature oak-hickory forest, noticing signs of its struggle against being overtaken by sugar maple and ironwood trees. Some of the oldest oak trees have experienced heart rot, a typical condition for old trees, and have fallen or lost large branches in recent wind and ice storms. The fallen trees were old before I was born, but as long as their seedlings survive to reach the canopy, future forests will be maintained with the same species assemblage and resemble today’s forest, though the actual canopy trees will likely be different individuals.

Prairie opening at Forest Park South Nature Preserve.

Eventually the trail entered an open area, part woodland and part prairie, that may be termed a savanna or barrens. The prairie opening follows the ridge line, especially on the south- and southwestern-facing slopes. Here I expected to see red-headed woodpeckers, who thrive in such habitats, but the woodpeckers were elusive or absent. From out vantage point at the prairie, we had an unobstructed view of a portion of upper Peoria Lake, which fills the river valley. Even with the beautiful view, I found it impossible to look upon the lake and not recall its many intractable environmental problems, not the least of which is the lake’s loss of depth due to siltation from watershed erosion. With recent heavy and frequent rains, the tributaries were all running high and muddy, and Peoria Lake has less volume with every passing day. How long this may continue, I do not know, but I hope that the day may not come within my lifetime for the lake to be shallow enough for black willow trees to survive, vanguards of a floodplain forest, where now there is only open water.

Barrens at Forest Park South Nature Preserve.

At the edge of the prairie opening, Julie and I sat on our favorite bench for a few minutes and watched a soaring red-tailed hawk. Several homes along Grandview Drive were visible from the bench, and I thought that any of those houses may not be a bad place to live; I wondered if we were being watched.

Before too long, we took the distant approach of two hikers as a signal to leave, and began our return hike. At our last view of the barrens opening, I stopped to look backward, to fix the view upon my mind, thinking about when I might return – hopefully many times over many healthful years. And I turned to Julie who said, "The hike felt good." Indeed, it did.