Tent caterpillar population expected to peak this year in northern Ontario

They're creepy. They're crawly. And they're back for another year.

Billions of tent caterpillars will be making northern Ontario their home and feasting on trees over the spring and summer.

The caterpillars have a decade-long cycle, ending with a population surge that can last as long as five years.

Even though they are a native species to northern Ontario, Science North staff scientist Dan Chaput says he still gets a lot of questions every time the population peaks.

"It's a natural cycle but, you know, people don't remember 10 years back and some people get panicky and we get all kinds of calls and emails," he said.

It's all natural

Chaput, who is also an entomologist, suspects the cycle will reach its peak either this year or next year before nature takes over.

"What happens is that their predators and diseases and all of these viruses and all that, they also peak," he explained.

"And then the population kind of gets wiped out, and then it starts over, it builds up slowly over the next 10 years."

Although people might be worried about their plants — or simply grossed out by the sheer volume of caterpillars — Chaput said there isn't much to do besides ride out the cycle.

He added that most trees that are eaten by the caterpillars won't sustain long-term damage, but there are a few options for people wanting to keep their plants safe.

Chaput recommends spraying the caterpillars with a solution of 40 parts water to one part dishwashing liquid, or using pest control products that contain Bt (bacillus thuringiensis), a bacteria that is toxic to the caterpillars.

"When you're dealing with literally billions of caterpillars there's not a lot that can be done," he said. "It's part of the natural cycle of the forest in northern Ontario."