Why there are so many forest tent caterpillars in Calgary this year

Añadido: 2026-06-03

[00:00:00]A resident of northeast Calgary took this up-close and personal video of the tent caterpillars in his backyard Thursday night.

[00:00:07]>> [music] >> And this large cluster of them in the northwest is just one of many posted to social media this week. But this video taken in the deep southeast sums it up.

[00:00:16]>> Ew.

[00:00:18]>> Forest tent caterpillars are usually found in northern and central parts of Alberta, but one entomologist says outbreaks happen about once a decade.

[00:00:26]>> I've been here 22 years and haven't seen anything to this extent in this area.

[00:00:31]>> They can last up to 3 years, and this year it looks like they've reached Calgary >> [music] >> in big numbers. Fry says the best way to remove them are scraping the insects off and freezing them or using a natural insecticide. This arborist says he sees forest tent caterpillars at least two or three times a week.

[00:00:49]>> Once they get out of control, it's very hard to like mitigate the issue.

[00:00:54]>> He says the caterpillars mostly land on fruit trees, starting at the bottom and making their way to the top, feasting on leaves and shoots along the way.

[00:01:01]>> Over the course of like a few years of something like this happening will cause a tree to go in such a rapid state of decline that we can't save it.

[00:01:09]>> This horticulturist says the sooner the caterpillars are dealt with, the better.

[00:01:13]>> Cuz they'll overwinter, they'll over season, and they'll come back twice as [music] much.

[00:01:18]>> The thought of seeing more of these caterpillar clusters might be the motivation Calgarians need to get rid of them.