Wild Profile: Meet the midge

Midge on a blade of grass glows in the back light Photo by StefanieMueller/Shutterstock

You might know midges as those tiny, unassuming bugs that grace spring evening strolls, backyard dinners, and outdoor picnics with their slightly annoying omnipresence. Their individual benignity becoming quite bothersome as they gather in overwhelming clouds of wings and spindly legs.

But what is this tiny insect’s purpose in life? Why do they fly around in buggy mobs, casting a shadow over outdoor spring activities? Do they bite?

Andrew Young, an assistant professor at Guelph University’s school of environmental sciences, answers our questions and assures us that yes, “they’re completely non-biting, they’re quite harmless. They don’t impact people at all, except for being a minor nuisance sometimes.”

Where do midges live?

The midge can be found in almost every corner of the earth. “They’re quite cosmopolitan,” says Young. Midges can be found wherever there is water because that is where they lay their eggs

The only places you won’t find midges are dry deserts, but even in the frozen wastelands of the Antarctic, you can find this resilient insect. “Midges are actually the largest land animals to live in Antarctica year-round,” says Young. Penguins would take the crown, but they don’t stick around all year, thus a species of wingless midge are the recipients of this honourable distinction. 

How long do they live and what times of year?

Midges first emerge in the late spring and early summer but different species and cohorts hatch at varied times throughout summer and into early fall, creating the illusion that they live through the summer.

In reality, this insect only lives for about two weeks after transitioning from a larva, which is colloquially known as a “blood worm” due to some species’ red colouration, into its fly form.

“You assume that animals spend most of their lives as an adult, like humans, but not midges,” says Young. “In many species of midge, they live for about a year as larvae.”

When they emerge as adults, they spend the warm months mating and feeding, but they live as water-bound larvae for the rest of the year. 

What do they eat?

In the various bodies of water midges call their winter homes, “they will spend their time filter feeding and eating bits of debris,” says Young. But come springtime, midges actually become major pollinators. 

Out there with the bees and the hummingbirds, these quiet little creatures feast on pollen and nectar from plants, as well as any other sugars in their environment, helping to pollinate essential plant species. Unfortunately, they don’t produce honey.

“If you’re in really cold ecosystems, like the Canadian Arctic or higher altitudes, like up in the mountains, they actually become one of the major pollinators,” says Young. “They’re quite beneficial. They’re just slightly annoying sometimes.”

What role does the midge play in the ecosystem?

In addition to being major pollinators, as larvae, midges are vital filter feeders. “They’re helping to cycle a lot of nutrients in the aquatic ecosystem as they feed on bacteria and microbes and pond muck,” explains Young. They also serve as a source of nutrients for some bottom feeding fish and small invertebrates that, in turn, get fed on by bigger fish in the food chain.

Midge larvae are also widely used in the commercial pet trade for purchase as fish food.

In their adult form, they continue to serve as an important source of food for many land animals including birds, bats, and frogs. “When you have this massive emergence of midges in early summer and late spring, that’s all biomass moving from the aquatic ecosystem into the terrestrial one, providing food for tons of other animals,” says Young.

Additionally, when consumed by other animals, midges eventually become fertilizer, in the form of animal waste, further aiding in plant growth and health. 

How do they mate?

Remember those buggy mobs we discussed ruining your evening walks? They are actually an essential part of these vital creatures’ lifecycles—it’s how they mate.

“They form those big meeting swarms, which are mostly made up of males, and then as the female enters the swarm, she’ll find a mate, and she’ll live just long enough to lay her eggs and die shortly after,” says Young.

The eggs are laid on the surface of the water before sinking to the bottom where they become larvae. About a year later, these larvae enter a pupil phase, “like a butterfly chrysalis, just less charismatic than a butterfly,” which float to the surface in the late spring or early summer. From these pupils a new generation of adult midges are born and live just long enough to reproduce and eat some pollen along the way.

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