As part of Browntail Moth Awareness Month, the Maine Forest Service is encouraging Mainers to snip the pests out of trees during the insect’s dormant season to reduce the impacts they have on people’s health.

Overwintering webs of the browntail moth caterpillar on a crabapple tree branch Photo from

This proactive step is especially important in hindering the invasive insect from spreading elsewhere in Maine as it has in the last seven years.

According to a 2021 study from the University of Maine and Maine Forest Service, browntail moths weren’t detected in Oxford, Piscataquis, Aroostook and Washington counties as recent as 2018. As of last year, Maine’s browntail moth population stretched over over nearly 200,000 acres, and the insects could be found in every Maine county except for York.

The largest browntail moth populations in 2021 were found in Androscoggin, Cumberland, Kennebec, Knox, Lincoln, Sagadahoc and Waldo counties. Pockets of large populations were centered in the Midcoast and Augusta regions, according to a 2021 survey from the Maine Forest Service.

Entomologists expect this year’s moth population to be “as bad or worse” than last year’s, said Maine Forest Service State Entomologist Allison Kanoti.

As caterpillars, browntails make nests in and feed on hardwood trees and shrubs, including oak, shadbush, apple, cherry, beach plum and rugosa rose. The insects can kill trees or stunt their growth.


In humans, they cause skin and respiratory issues.

The caterpillars have microscopic, toxic hairs that break off and become airborne or settle on surfaces in infested areas. When those hairs land on humans, they can cause a skin rash similar to a poison ivy reaction as well as breathing problems, according to Kanoti. Those symptoms can last anywhere from a few hours to several weeks and can be severe in some individuals.

Browntail moth nest. File / Portland Press Herald

The Maine Department of Health and Human Services suggests a cool bath with baking soda, hydrocortisone cream and calamine lotion can help symptoms.

Browntail moths are active from mid-April to early October, according to the Maine DHHS. To lessen the impact of browntails, the state advises Mainers to look for and dispose of any webs on their property during the winter.

The caterpillar’s webs can look like single leaves hanging onto twigs or fist-sized clumps of leaves tied together tightly with silk. The webs should be cut out of trees and put in soapy water for several days before being thrown away, according to guidance from the Maine Department of Agriculture, Conservation and Forestry.

Browntail moths were accidentally introduced to Somerville, Massachusetts from Europe in 1897, said Kanoti. By 1913, the insect spread to every New England state, New Brunswick and Nova Scotia.


Though the population slowly decreased in the early 1900s until they were cornered on Cape Cod and a few Maine islands, the population started growing again and have been in an outbreak phase since 2015, said Kanoti.

Brunswick Arborist Dennis Wilson said he’s noticing more trees around town with browntail webs compared to prior years. The infestation level, however, has remained light in all the trees he has seen so far, meaning the insects likely won’t impact the trees’ health.

“It’s not terrible by any means, but I’m seeing more trees with light infestations,” said Wilson. “They’re not going away, but it’s manageable if people stay on top of them. Between February and April, it’s good to walk around your yard with a pair of binoculars and see if you can find any webs.”

Wilson said he keeps an eye on trees around town, including trees near schools, and treats them when needed.

After one of Maine’s worst browntail moth seasons, there are signs 2022 could continue a years-long outbreak of the invasive insect responsible for painful skin rashes and occasional dangerous breathing problems. But winter and spring weather could determine the scale of next summer’s infestation. Photo by James Dill

State Rep. and Woolwich Selectman Allison Hepler sponsored a bill that would provide funding for communities to specialists and rent equipment to remove nests.

Hepler said the idea for the bill stemmed from conversations she had with local residents who had browntail moth rashes, some of whom were considering cutting down their trees to get rid of them.


“It started four years ago in a Bath YMCA locker room,” said Hepler. “Someone was talking about the browntail moth rash she had and before you knew it, there were ten of us talking about browntail moth rashes. For the most part, I found people were just suffering with it.”

Hepler said a statewide approach would make more progress, as some Maine communities don’t have the budget to hire an arborist or issue regular warnings.

“If I just cut the trees in my neighborhood, that’s not going to do much,” said Hepler. “Treating them needs to be a coordinated effort. It was a way for towns to feel like they were doing something about this.”

Hepler’s bill unanimously passed the Maine Legislature Committee on Agriculture, Conservation and Forestry on Tuesday, Hepler said, and will next head to the funding table.

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