Tent caterpillars are infesting Aroostook County again

3 weeks ago

In the early 1980s, anyone in Aroostook County had only to utter two words to make people cringe: tent caterpillars.

Black, blue and yellow-striped forest tent caterpillars surge every few years. Now they’ve returned with a vengeance to northern Maine.

People throughout Aroostook County are reporting infestations so extensive that the insect larvae cover trees and buildings. Despite the “ick” factor, they’re harmless to humans. But as they crawl by the hundreds, they want only one thing: fresh, green leaves. An army of caterpillars can eat enough leaves to do some damage — and then they turn into moths and lay eggs.

“The problem is, with this many around this year, in another two or three weeks you’re going to have these little brown moths flying all over the place,” said Jim Dill, director of the Diagnostic and Research Laboratory and pest management specialist with UMaine Cooperative Extension. “If you have enough of them, what ends up happening is a possibility of an even bigger outbreak next year.”

WASHBURN, Maine — May 31, 2024 — Forest tent caterpillars cluster on a tree in Washburn on May 31. They crawl and gather in large groups and eat tree leaves. (Paula Brewer | The Star-Herald)

The species is one of two tent caterpillars native to Maine. While Eastern tent caterpillars build tents, forest tent caterpillars don’t, he said. Instead, they lay down a kind of silk in the trees as they’re moving around. 

The insects feed on birch, poplar and other similar trees, and can leave them nearly bare. Those species can withstand two to three years of defoliation and may not die, Dill said. After the second or third year of leaf-stripping, though, some lasting damage could result.

The caterpillars come in cycles and usually diminish naturally, he said. They become food for insects, mice and other animals, and weather can play a part. If there’s a wet spring next year, for instance, fungus or bacteria might eradicate most of the population, he said.

Dill remembers The County’s massive outbreak in the 1980s. It got so bad public works crews actually sanded the roads because they were so slippery with run-over caterpillar carcasses, he said.

Right now, there really isn’t much people can do about them except wait them out, because they’re nearing the end of their caterpillar stage, he said. They’ll spend two to three weeks in their pupal stage and emerge as forest tent caterpillar moths later in the summer.

This year’s outbreak is the worst David Michaud of Caswell has seen since the 1980s. From his home he can look north to the Canadian border and see some hardwood trees, like maples, thriving while others have bare branches.

“One minute they weren’t here, and the next minute they were in swarms,” he said. “They’ve been causing a lot of destruction here.”

CASWELL, Maine — May 31, 2024 — Hardwood trees in Caswell show evidence of defoliation from forest tent caterpillars on May 31. (Courtesy of David Michaud)

The caterpillars have exploded at his home within the last week, he said. He has about 10 poplar trees that now have no leaves left. 

He has seen the silklike strands they leave in trees. He can’t walk in his woods right now because he’ll be covered with them, he said.

He tried spraying some of the smaller trees, but didn’t find that very effective. He took a leaf blower to the caterpillars when they started crawling on his house. It worked for a bit, but more came back.  

If their trees have been stripped by the caterpillars for more than two years, Mainers may consider insecticides, but should consult a licensed applicator, Maine Forest Service staff said in their “Living with Caterpillars” bulletin issued this month.

Homeowners can get rid of them in other ways, such as washing them off with a substantial force of water, using a little soap or stiff brush, or even with a shop vacuum, according to the report. But the best option is simply to wait until they disappear naturally.

Brianna Mejia-Bouchard was shocked Friday when she pulled up to the drive-thru window at the Caribou Walgreens and saw thousands of the critters crawling on the building. 

Washburn District High School English teacher Holly Robbins had the same reaction when she took her students for an outside lesson this week and the caterpillars were all over. For some of the kids it was a novelty. For others, not so much.

“It’s a little bit disconcerting when you see the ground move,” she said. “It felt like you couldn’t step anywhere without squishing them between your toes.”

If you can’t beat ’em, maybe the best thing to do is take the whole thing with a sense of humor. That’s what Evergreen Lanes/Rendezvous Restaurant in Caribou did Thursday, when they posted a mockup photo of their “newest creation” on their social media page: a pizza that looks like it’s garnished with the caterpillars.

“Don’t miss out on this limited-time culinary experience,” the post stated. “It’s ‘in-tents.’”