About those midges

My last post mentioned that midges, besides mayflies, were hatching on Birch Lake recently. Midges of course are tiny white flies that when on the wing look like mobile bits of cottonwood fluff. Believe it or not, trout fishing enthusiasts (or should we say fanatics?) actually tie flies small enough to mimic these things.

While the mayflies at Birch were hatching a week or so ago, the midges were, too. One day hundreds of them clung to the screens of our lakeside porch; a tap on the screen sent them flying; in a few moments they were back. The next day only a few remained. I’ve been down on the lake when midges were thick, a swarm hovering around my head, and if I listened carefully I could hear a faint, collective buzzing.

These were non-biting midges, from the insect family Chironomidae, and often called chironomids. Some call them “blind mosquitoes”; others call them “fuzzy bills” because of the males’ bushy antennae. As with mayflies, if your lake has midges, that’s a sign the water quality is pretty good. Midges are an important link in the food chain in and around a lake. Fish and predatory water insects eat them, and the midge larvae help keep the water environment clean by eating organic debris.

Like mayflies, midges have interesting lifecycles. The adult flies lay gelatinous masses on eggs on the water surface, each holding as many as 3,000 eggs, which sink to the bottom and hatch in about a week. The larvae dig into the mud or, in some species (and there are many) build small tubes to live in. They feed on organic matter suspended in the water and mixed with the bottom mud. As they grow, they turn pink and eventually dark red, at which point they are known as bloodworms. The color comes from hemoglobin, the same compound that makes our blood red; it allows the larvae to “breathe” in the mud, which of course is low in oxygen.

After two to seven weeks (largely depending in water temperature) the larvae become pupae. About three days later, they swim to the surface, and adults emerge within several hours. The adults then mate; they live only three to five day and do not feed. In the heat of summer, midges may complete their lifecycle in as little as two or three weeks. Fall larvae do not pupate but instead remain in the larval stage until spring.

Have you seen midge hatches on your lake? Watch for them throughout the summer – several generations may hatch before the season turns to autumn.