Thursday, June 4th 2020, 9:00 am - Every year without fail, thousands of these little flies emerge and cover everything from trees, to rocks, to sides of homes along the lakeshores. This year people have really taken notice of them, but experts say there aren't more of them than usual.
Every year around the end of May we see an emergence of little flies swarming the lakeshores of the Great Lakes and other smaller lakes around Ontario.
People call them all sorts of names and have the misconception that they are all the same.
“I will have to give you a scientific name: Chironomus plumosus,” said Stephan Marshall, a retired professor of entomology at the University of Guelph. “It's got a number of vernacular common names. Lake flies is one common name people call them around here some people call them fish flies, but that's confusing because we also will apply that name to another aquatic insect that will emerge by the million in about four weeks from now. Mayflies, even more abundant than the midges.”
It may seem like there are more midges this year than any other year, but that’s not necessarily the case.
“It's one particular species of chironomid midge. Now there are other species of chironomid midges emerging all the time from February through to December. I'm sure that the populations vary from year to year due to a variety of causes but I don't see this being any more abundant this year than any other year,” said Marshall.
Although the midges may be a bit of a nuisance, they are crucial to the nutrient cycle and they provide food for fish and birds as well.
“People will appreciate their importance as bird food because I think a lot of people understand how a lot of insect-eating birds have declined in the past few years,” explained Marshall. “Many insects have declined in the last few years, so to have a species like this which is arriving in great abundance for at least a couple of weeks, is a very good thing.”
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THE LIFE CYCLE
The midges are phenomenally important to the Great Lakes and they begin their life cycle in the muck at the bottom of the lakes.
“They make these cool little silkin tubes, like salivary secretion tubes, and the filter stuff algae and organic material from the muck in the bottom of the lake, feed on that and develop until the fall and then they slow down in the cold months of winter and then they sort of boot it up again when the ice goes out in Spring and finish their larval development,” said Marshall.
They then form into a pupa, and once they are ready to go, they come to the surface and the adults emerge. This happens every year at about the third week of May.
“The males form these massive swarms and they hang out in these big swarms sort of dancing up and down until a female comes in and then they drop out, mate quickly,” Marshall explained. “The female goes back out over the water and drops eggs onto the water surface.”
He said the masses that you see on the lakeshore are probably mixed males and females that have blown onto shore.