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Browntail Moth Infestation Expanding in Maine

Courtesy, Maine.gov
A browntail moth larva with its sticky, prickly hairs.

It’s expected to be a banner year for browntail moths, according to the Maine Forest Service. The invasive insects can pose health problems for trees and insects, and stopping them is difficult.

Last fall, Maine Forest Service entomologist Charlene Donahue wanted to see just how much damage browntail moth caterpillars were causing by munching on the leaves of hardwood trees and shrubs. So, she did an aerial survey.

“In September, when the little teenie weenie caterpillars that are about a twelfth of an inch long were feeding, and mapped over 11,000 acres of feeding damage,” she says.

That means when those formerly teenie weenie caterpillars emerge from their webs this spring and get big — two inches long — they’re going to defoliate a lot of trees. Donahue says most browntail moths are centered in the Topsham, Brunswick and Bowdoinham areas of the state, but the infestation has expanded.

“As far as Kittery, inland to Lewiston, Auburn, Turner, up into Augusta, Waterville, Winslow, Turner,” she says.

And while that’s bad news for trees like oaks and apples, it’s also bad news for people because the caterpillars shed hair that can cause poison ivy-like rashes and breathing problems if ingested.

“The hairs can last for a year or 2-3 years, so people — even if the browntail moth go away — they go and rake or work in the brush in a place that’s been infested in the past, you can still end up with a rash,” Donahue says.

The severity of this year’s infestation is prompting the town of Cumberland to consider spraying pesticide in an area of town most affected, Cumberland Foreside.

“This is something that happens every few years, and we try to be proactive.” says Peter Bingham, chairman of the Cumberland Town Council.

Bingham says Cumberland has considered spraying in the past, but abandoned the plan after too many homeowners opted out. The town is holding a workshop Monday night to help determine whether to spray this time around.

Donahue says using pesticides would provide relief for people in the area, but it won’t get rid of browntail moth entirely. They’re invasive, from Europe, and don’t have natural predators.

“It’s been here for well over 100 years and it’s still a problem,” she says.

The only thing that seems to put a dent in browntail moths is a fungal disease, which hasn’t been as prevalent in recent years.

Donahue says to avoid exposure, mow the lawn when it’s wet. Don’t hang laundry outside where it can pick up the caterpillar’s hairs. And wear long sleeves and pants if you’re in an infested area.