Swarms of midges invade Toronto for annual mating ritual

Harmless insects are mostly a nuisance during warmer spring months

Published Apr 30, 2026  •  Last updated 1 hour ago  •  2 minute read

A non-biting midge. The Canadian Encyclopedia

There are many joys of living close to Toronto’s waterfront and rivers.

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The springtime swarms of tiny flies called midges is not one of them.

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As the weather begins to warm up in April, insects of the Chironomidae family found on lake and river beds begin life as larvae and feed on sediment before transforming into pupae.

Once the bugs become adults, they leave the water and take to the skies in large swarms. Typically, males emerge first and wait for females to arrive for their annual mating ritual.

Nuisance but harmless

“Because of these swarms, non-biting midges are often considered a minor nuisance to humans, although they are harmless,” according to The Canadian Encyclopedia. “Adults of most species are very short-lived, surviving just long enough to mate and lay eggs.”

Midges that bite are called Ceratopogonidae while gall midges, which live and feed inside of growths on plant tissues, as known as Cecidomyiidae.

Females are known to bite humans, mammals and birds similar to a mosquito’s sting. While not easily repelled by chemicals, leaving the area is the best way to avoid being bitten.

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“Non-biting midges form huge mating swarms in the evenings,” the Canadian Encyclopedia says. “These swarms can become so large that they resemble clouds of smoke.”

Food for fish and birds

While midges may be a nuisance during the spring and summer months, they play an important role in the ecosystem by providing food for fish and birds.

Ontario boasts more than 800 species of midges, but only a few call Toronto home.

For people who live by a watery area, one way to keep midges away is to turn off unnecessary lighting as they are attracted to sources of light. However, that may not stop them from gathering on windows, doors, and exterior walls.

Other tips to keep them out of sight is to use yellow lighting and ensure window screens are in good shape.

If a person does encounter a swarm of midges, it is best to keep your mouth closed to avoid swallowing them, especially if you are riding a bicycle.

Toronto resident Paul Jones filmed a swarm of midges along the lakefront in Ajax on Tuesday and shared it to Facebook.

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