Ick factor: Tent caterpillars invade Sask.

For some, it’s the stuff of nightmares: hundreds of caterpillars huddled together on tree trunks or hanging down from branches. 

For people in Saskatchewan, it’s an everyday reality. 

Before Lacey Hickson left her Warman home for the long weekend, she noticed forest tent caterpillars already moving in on her trees. 

“When I got back, about half the trees were eaten from the top down, and the trunks of the trees were completely black – it was like fur,” Hickson said, adding she’s also encountered the bugs in downtown Saskatoon. 

“I could see them hanging from the trees, and I looked down and there was one on my arm. For the rest of the day it felt like my head was itchy and they were crawling on me.” 

Outbreaks of forest tent caterpillars typically last between three to seven years. City officials say Saskatoon is currently in year four.  

Businesses downtown are also feeling the ick factor. Jensine Trondson, who works at White Dahlia, encountered the caterpillars recently while putting out sidewalk signage for the clothing boutique.

“I put the sign up, then turned around and they were already all over the door handle of the store,” she said. “You could see customers panicking and then with one finger, pry the door open.”

Saskatoon’s Jessica Mcghee recently went for lunch on Broadway and spotted the pesky insects.

“I thought the ground was moving because there was so many of them,” she said. “We started freaking out because caterpillars were crawling everywhere and they’re pretty nasty.”

While the disgust level is high, the risk to trees isn’t. While they might experience heavy defoliation, unless there are underlying issues, trees should recover.

The City of Saskatoon doesn’t control for cankerworms, forest tent caterpillars or leafrollers, since the insects don’t pose a health risk to the trees.

What are these monsters?

Homeowners have most likely encountered the blue-streaked forest tent caterpillars already. The bugs feed on a large variety of trees including ash, poplar and chokecherry.  

Cankerworms – also known as loopers and inchworms – are found primarily on the leaves of American elm and Manitoba maple trees.  

The fall and spring cankerworm species often feed together during June and July. They can be found hanging from silken threads underneath infested trees and can be a nuisance.

Leafrollers feed while concealed within leaves that are rolled or tied together with silk webbing. Ash trees are their preference, but they also attack other tree species.  The larvae will feed in mid to late June, but the leaves remain rolled throughout the summer.

What can you do?

While tree banding can be used to control cankerworms, it’s not effective against leafrollers and forest tent caterpillars.  Those insects have wings and fly from tree to tree to lay their eggs.

According to the city, the best time to place bands on trees is from September to May to help prevent wingless adult female cankerworm moths from climbing host trees to lay their eggs.  

Bands should be removed at the beginning of June because they can collect moisture and cause the trunk to rot. 

The city said home owners who want to control the insects on their own trees should consult a local garden centre for advice.  

Information is available through the city website on Dutch elm disease, wildlife, tree defoliators and urban pests such as mosquitoes.   www.saskatoon.ca/pests.

– With files from 650 CKOM’s JT Marshall.