Klamath Midge

Nature Notes by Dr. Frank Lang

It’s early evening, the wind dies, and near the edge of the marsh a few small flying insects rise. Soon joined by others, the swarm increases and increases and increases until the mass of insects forms a long symmetrical top-shaped mass that swirls about emanating a strong, screaming hum audible at a distance of 100 yards. Cows refuse to eat. Automobile radiators clog. People become nauseated and have trouble breathing.

Where could this happen? Belize, the Mosquito Coast? The swamps of the Congo? The banks of the great gray-green, greasy Limpopo River, all set about with fever trees? Give up? It’s the Klamath marsh!

What I have described is the mating frenzy of the Flamath midge, Chironomus utahensls, taken from a 1941 paper on the biology of the insect. Perhaps the description was a little overdone, or perhaps conditions have improved somewhat since 1941. For many Klamath residents and visitors, however, the midge is still a nuisance.

Although these tiny midges superficially resemble mosquitoes, they are quite different. When they alight they raise their forelegs and not their hind legs as mosquitos do. Midges are not interested in a blood meal, although you may inhale several by mistake. The larvae of midges are often bright red, the blood worms sometimes used by aquarists for feeding tropical fish.

The shallow, nutrient-rich waters of the Klamath aquatic ecosystem support enormous numbers of algae: desmids, diatoms, and especially, a planktonic filamentous blue-green algae, Aphanizomenon, as many as 20 million filaments per cubic meter.

All these producers (photosynthesizing plants that put energy into food webs) support and sustain the entire ecosystem, especially the midge larvae – millions and millions and millions of midge larvae. Midge larvae that filter out desmids, diatoms and the bacteria that flourish when the blue-green algae decompose. Midge larvae that are eaten in turn by all 18 species of fish in Upper Klamath Lake, especially the Klamath chub and the Klamath roach which are preyed upon by trout, huge trout, trophy trout for which Klamath Lake is famous.

Other consumers (animals that eat producers a other consumers), aquatic beetles, dragonfly larvae, a small marsh birds also use midge larvae for food. consumers are in turn eaten by other animals. adults are eaten by adult dragonflies, songbirds, toads, and spiders – all part of the Klamath Lake food web.

Insects, no matter how important ecologically, can be a bother. Efforts to control their numbers through modern chemistry have frequently been attempted; however, no major efforts have been made to control the Klamath midge in Oregon. The insect carries no known diseases and does not bite. It is just a nuisance. If the midge is an aggravation, try to find some solace in the important role it plays in the biology of Klamath Lake and the production of trophy trout.

— Dr. Frank Lang

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