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Here’s why Torontonians are seeing more midges this time of year, especially near Lake Ontario, as well asÌýwhat the insect is actually up to and what it means for our environment.Ìý

What are the midges in Toronto?

While there are many different species of midges across Ontario, the ones coming out in large numbers around º£½ÇÉçÇø¹ÙÍøwaterways is usually one specific family of species called theÌý“Chironomidae,” commonly known as the “non biting”Ìýmidge, said Darryl Gwynne, emeritus professor of biology at the University of Toronto’s Mississauga campus.Ìý

What we’re seeing now are probably midges that were living in the sediments of Lake Ontario as larvae, said Douglas Currie, curator of entomology at the Royal Ontario MuseumÌýand U of T professor in the department of ecology and evolutionary biology.

Some species might have multiple generations, meaning you might see them several times throughout the year, said Currie, while other species might only have one generation, come out at a particular time of yearÌýand then die off.

What’s up with the swarms?

“As is almost always the case in the animal kingdom, it’s all about sex,” said Gwynne. For midges, this period in mid-spring is prime mating season.

To maximize their success at finding a mate, said Currie, the males will form large swarms to attract the females, who then fly into them to mate.Ìý

Sometimes “it might look like a column of smoke” forming inside the swarm, said Currie. The males organize themselves over “what we call a marker,” he said, which could be a tree or a big rock that the insects choose as their focal point to fly around.Ìý

“That’s why we’re seeing such large populations coming out now. But, as quickly as they appear, they will disappear because they are so short-lived,” said Currie.

People don’t tend to pay as close attention to the insect world, said Gwynne, “where you get really amazing phenomena like swarming going on as well — or group sex I should say — where the males are in one place.”

“They’re in a great situation, the females,” added Gwynne, noting they can enter a swarm and choose whatever male they want to mate with.

How long do they live?

Midges have aquatic larvae that live on the bottoms of lakes, said Gwynne. They also live in streams, rivers and ponds.

Most of the lifespan of a midge is spent in the water, said Currie. In fact, “most of their life history is spent in the larval stage in the water,” he said, adding they can last as larvae from just a few months into years.

When they do come out as adults to mate, they only last a few days to maybe a few weeks at most, he said.

Midges, similar to other insects like butterflies, moths, flies and beetles, have “four life history stages, egg, larva, pupa, adult,” said Currie.Ìý

“The larval stage is the immature stage where they feed and go through a series of moults until they reach the pupal stage,” he said.Ìý

In the pupal stage, midges do not eat. “They form a pupa, like the equivalent of a chrysalis in a butterfly,” said Gwynne, then they hatch out as the flying adult.

When they emerge, the adult stage is “typically focused on mating,” said Currie. Each female midge can produce up to hundreds of eggs.

This, continuedÌýCurrie, is not the case with mosquitoes and black flies for example, which are insects that “normally require a blood meal to reproduce successfully.”

Midges are a good sign for the ecosystem

Midges are a sign of a healthy ecosystem even though their lives are short, said Currie.

“Midges are really important in ecological communities,” said Gwynne, “for fish and other things as a source of food.” Salamanders, alsoÌýbreedingÌýduring this time of year, feed on midges larvae from the bottoms of ponds, he said.

Midges are incredibly important components of the aquatic food webs, not only in Lake Ontario but also in ponds and rivers and streams, said Currie.

And it’s not just fish relying on midges as a life source in the food chain.Ìý

“There’s a whole bunch of predatory insects, such as dragonfly larvae,” that probably eat midges as well, said Gwynne.

It’s almost a guarantee, said Gwynne, that nesting birds are eating midges, with bats at night likely honing in on eating midges as well.

“The apparent inconvenience that we suffer from them flying into our eyes or nose or mouth,” said Currie, “is a small price to pay for a healthy ecosystem.”

Tips for dealing with midges

• Remember, midges (chironomidae) do not bite
• If caught in a swarm, close your mouth. You don’t want to breathe them in, said Gwynne. “There’s lots of them so you can sometimes take them into your mouth.”
• Midges can get attracted to light at night, said Currie. If you leave a porch light on for example, this could be drawing them closer to your home.Ìý
• Make sure your windows are shut or that you have screens on your doors, patio doors and windows.Ìý