Lake Erie is known for its regular occurrence of these beetle clouds, which occur from May to September. By Julia Soeder

It’s a bird. It’s a plane. False alarm, it’s a swarm of mayflies and mosquitoes. When the air gets cooler and wetter in northeast Ohio during the summer, these two animals leave their home on the bottom of Lake Erie to live out of the water for a few days. When enough mayflies or mosquitoes swarm at once, they show up on weather radars in northeast Ohio, says meteorologist Rick Garuckas of the National Weather Service Cleveland.

“A radar sends out a pulse of energy that looks for particles or objects in the atmosphere, whether they’re raindrops, hailstones, snowflakes – or it could be other objects, like insects or any dirt in the air,” he says. “Insects are small; the radar won’t be able to detect individual insects. But if there’s a big cloud of them, like a swarm of mayflies or mosquitoes, it’s dense enough for the radar to reflect it back, and we’ll see a bright green or blue return.”

It has become an annual tradition for mayflies and mosquitoes to appear on weather radar during the summer in northeast Ohio. Mayflies are generally much larger than mosquitoes and are a sign of a healthy lake because they are sensitive to pollution. Mosquitoes usually show up earlier and form loud, buzzing clouds that are attracted to light.

“You usually see them in the evening at sunset when they rise into the sky and form swarms or large clouds – and that’s the time when we usually see them on radar,” says Garuckas.

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(Photo courtesy of SR Photies via Flickr)

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