What will this cold snap mean for our bugs?

The Prairies Climate Change Project is a joint initiative between CBC Edmonton and CBC Saskatchewan that focuses on weather and our changing climate. Meteorologist Christy Climenhaga brings her expert voice to the conversation to help explain weather phenomena and climate change and how they impact everyday life.

The last few weeks have felt like an early welcome to spring. Thawing temperatures began to eat away at the snowpack in Alberta during the first few weeks of February. 

But this winter has another trick up its sleeve. A deep freeze moving into the province this week will drive the mercury down to the minus 20s or even minus 30s. 

"The cold air is very close now and we're going to see temperatures well below normal to finish this month," said Kyle Fougere, meteorologist with Environment and Climate Change Canada. 

While many of us can reach back into the closet for our parkas, plants and animals are not quite as lucky. What will this late and abrupt cold snap mean for insects that are weathering the winter?

Winter cold and wild things

During the winter, some insects will burrow deep into the ground, waiting for warmer weather. Some remain awake.

"Our wolf spiders, springtails — a bunch of different things are actually active under the snow and we just can't see them," said Peter Heule, live animal supervisor at the Royal Alberta Museum. 

Invertebrates survive by producing a kind of antifreeze or a cryoprotectant in their bodies.

"Antifreeze is going to mean that your body tissues will remain liquid even when we're below zero. And then the cryoprotectants basically allow ice crystals to form in your body, but not in places where they're going to cause damage," he said. 

Even with those adaptations, insects also need a layer of insulation, seeking refuge just under the snow or leaf litter of a yard. 

A winter marked by wild swings

We know that bugs are impacted by cycles of thawing and sudden deep freezes. And there has been no shortage of either this winter, with temperatures that spent very little time around the "normal" mark. 

A warm autumn hit a U-turn in December with a deep freeze pulling temperatures into the minus 30s.

"It was actually very cold in December for Alberta and especially those first three weeks," said Fougere. 

As the calendar switched over to 2023, the weather also flipped, with warmer southern air and cloudy conditions helping to insulate the province.

"From about the 25th, 26th of December, we had a full, one-month period where it was near normal or slightly above normal for Alberta," said Fougere. 

"This milder trend has continued for the first couple of weeks of February."

That luck had to run out eventually. This week, cold Arctic air will push into Western Canada.

"For the next couple of weeks, we're not sure exactly where the coldest air is going to be," Fougere said, "but it's likely that we're going to see Arctic air spread over the Prairies and indications are that it could be longer lived."

And this particular cold snap is expected to have some staying power with frigid conditions looking to last out the month and forecasts calling for a cooler-than-normal spring. 

"It's pretty common this time of year to have these pretty large swings in the weather," said Fougere.

The promise of spring

When winter includes wild swings in temperature, we can see higher mortality rates in the insect populations. The full impact of this winter's fluctuations won't be known until spring. 

"Sometimes overwintering or hibernating is a risky business," said Heule. "If you don't choose the right site, you might not make it all the way through."

Heule said that insects like pupating caterpillars that turn into moths and butterflies may come out early in long warm stretches and perish as they are unable to find host plants, but others can adapt. 

"Wolf spiders might come out of the leaf litter and scurry around. And then as those temperatures start to drop, they might be able to find their way back to some other sheltered site or the original place they were hiding out," he said.

"But you certainly wonder how many of these things are going to be able to find their way back to shelter or maybe get stuck in those cold temperatures."

And as for the bugs you want to see in your yard to help your native plants thrive, Heule said there are ways to protect those insects from winter variability, such as melting snow. 

"I put all of the leaf litter and all the fallen leaves into my garden beds to sort of act as a more reliable blanket than the snow and I find a lot of [insects are] using that insulation."

Our planet is changing. So is our journalism. This story is part of a CBC News initiative entitled "Our Changing Planet" to show and explain the effects of climate change. Keep up with the latest news on our Climate and Environment page.