June 18, 2026

Forest tent caterpillars, or “t’angoo dughai” have been spotted massing on deciduous trees locally, and across the west of Canada this summer, returning after an approximately 10 year cycle. If you find them yucky, luckily this year’s cycle will soon be over, but next year could support them in larger numbers. Photo Credit - Ian Gregg

Caterpillars have inspired many-legged creativity from children’s books, famous literary characters, theories involving government intervention, culinary exploits, to the Stranger’s rockabilly hit The Caterpillar Crawl. Perhaps more commonly, forest tent caterpillars inspire revulsion in those who happen upon a writhing infestation of them roughly every ten years. Locally, they’re doing just that as their blue-striped presence has re-emerged. They’re even making appearances as far away as Chetwynd, Calgary & Edmonton this June 2026. While it’s evident that many people find forest tent caterpillars yucky, CFURadio wondered if they pose any serious threat to people, the environment, or the plants they actively munch on.

Dr. Dezene Huber, an entomologist in the University of Northern British Columbia’s Ecosystem Science and Management Program spoke with us to essentially say, “No.” While their presence may be alarming, they do have a number of natural enemies which eventually bring their numbers down, all are an integral part of the ecosystem, and the critters have been present long enough locally to earn the Lheidli Dakelh name “t’angoo dughai.” While the forest tent caterpillar can cause allergic reactions in some people, and stress the trees after repeated outbreaks, ultimately, “a lot of forest insects, things we call pests, things like the mountain pine beetle,” said Huber, “they’re just here in low levels doing their thing. You’d have to go look hard for them to find them nine years out of ten, but then suddenly they show up and everyone is like, ‘Where did they come from?’ Well they were here. They just haven’t… they haven’t left.”

Meanwhile these arthropods will continue to munch until they mature into moths later this month. At which point they will lay their eggs, locally, and we will get to see if our environment can support their numbers next spring or not. Have a listen for lore, curiosity, and hopeless prevention tips.