Massive mayfly swarm seen leaving Lake Erie on weather radar | Michigan Radio
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Massive mayfly swarm seen leaving Lake Erie on weather radar

Jul 8, 2019

May they fly away one day soon, but today mayflies are among us. Some are calling it an "invasion," but it's the time of year where cities and states near the Great Lakes region experience a repulsive visitation.

When an excessive amount is swarmed together, mayflies look like a thick large patch of dirt, and can be spotted on weather radars.

The Hexagenia genus mayfly species resides and hatches around the Great Lakes in late June and early July.

Billions have hatched in recent weeks and days, and have been caught on National Weather Service radars over Lake Erie. A specific hatch from June 27 was tweeted by a University of Notre Dame a biometeorology research assistant professor:

They emerge out of water ranging in size from about a quarter of an inch to a just over an inch to live out their adult lives lasting anywhere from minutes to a few days. They mate inland, and can be found around light.

Mayflies don’t bite, but their swarms are hard to ignore, are an annoyance to residents, and are considered traffic hazards because of the slippery conditions they cause when run over in a large amount.

These swarms reveal good water health and low pollution in the Great Lakes.