NEW BALTIMORE (WWJ/AP) – The fish flies’ return to lakeshore and riverfront areas of southeastern Michigan might bother some landlubbers but it bodes well for water quality.
The insects, also known as mayflies, are out in force in areas along Lake St. Clair, Lake Erie, the St. Clair River, and the Detroit River. The flies cling to streetlights, sidewalks, walls, boats, windows, trees and, perhaps most annoyingly, to people.
Michael Thomas, a fisheries research biologist at the DNR’s Lake St. Clair Fisheries Research Station in Harrison Township, said the insect’s late June return indicates waterways are in good shape.
“When you have a healthy population of mayflies or fish flies like we have here… that’s a sign that you have lots of oxygen available for living organisms [in the water],” he told The Detroit News.
The insects are also a valuable source of food for fish and birds, Thomas said, further cementing their importance in the ecosystem.
Fish flies emerge after spending one to two years on the bottom of a lake or river as a nymph living burrowed in the mud. When they’ve reach adulthood, the insects can fly, but they only live for 24 hours to seven days, depending on the species. During this time, their purpose is to reproduce.
The flies have large, transparent wings and measure about one inch long, with tails range from one-half to three inches in length. They’re often seen in large swarms.
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