A browntail moth caterpillar nest hangs on a tree Tuesday in the Androscoggin Riverlands State Park in Turner. Andree Kehn/Sun Journal

TURNER — Browntail moths are making their presence known this year and gone are the years when the pesky insects stuck to the coastline.

The browntail caterpillar, the larvae stage of the moth, is of most concern for the health of both humans and forests. The brown caterpillar has a white stripe on either side of its body and two red spots and sheds tiny poisonous hairs that can cause topical rashes when they come into contact with skin and respiratory irritation if inhaled.

The caterpillars also munch on the leaves of a number of types of hardwood trees and shrubs, which defoliates them or even destroy the tree entirely, according to the Maine Department of Agriculture, Conservation and Forestry.

Since 2015, the browntail caterpillars’ impact on tree defoliation has reached a level severe enough to be considered an outbreak.

Not only are the number of caterpillars increasing, but researchers are finding populations in central and western Maine for the first time since the caterpillars were identified in the state over 100 years ago.

Surveys conducted by the Maine DACF earlier this year and published in April found overwintering browntail moth webs — nests that protect the bug through the cold months — in every county in the state and the highest populations in Androscoggin, Cumberland, Kennebec, Knox, Lincoln, Sagadahoc and Waldo counties.

Browntail moth and browntail moth caterpillar are sometimes used interchangeably. The health concerns are related to when the browntail moths are in the caterpillar stage of its life.

The unusually hot and dry weather might be to blame, said state entomologist Allison Kanoti.

“It’s really good for many caterpillar species. They escape disease, they develop more rapidly, they even escape their natural enemies,” Kanoti said.

Drought conditions in 2020 and into 2021 have prevented the development and spread of a naturally occurring fungus that helps control the caterpillars’ population. Minimal precipitation also lowers trees’ ability to recover from defoliation, leading to deforestation in some parts of Maine.

Kanoti said that research from the University of Maine shows a connection between warmer late summer temperatures and population growth.

“I think that climate change is certainly contributing to what we’re experiencing with browntail moths.”

A browntail moth caterpillar climbs across a leaf on a tree Tuesday in the Androscoggin Riverlands State Park in Turner. Andree Kehn/Sun Journal

Aerial and ground detection surveys from the DACF showed that from late 2019 to late 2020, the presence of the caterpillars grew significantly in Auburn, Leeds, Minot and Turner.

In 2019, for example, the DACF found intense browntail moth activity across 89 acres in Turner. By November of 2020, that had increased to 16,271 acres.

There aren’t great records from the early part of the 20th century, so it’s difficult to that period with the last six years, Kanoti said.

“Certainly, it’s worse than any (season) I have experienced,” she said.

Turner Town Manager Kurt Schaub said Tuesday that the Selectboard had authorized him the night before to begin the process to receive a declaration from the Maine Center for Disease Control and Prevention that browntail moths are a public health nuisance to the town.

“I do not know at this time what steps will be taken at the state level to assist with the management/eradication of the problem, but we have to take the steps the state outlines before public resources can be used to address it,” Schaub said.

The Maine CDC defines a public health nuisance as “any activity or failure to act that adversely affects public health” and a declaration of such would give the town authority to take certain actions to control browntail moths.

Officials from Minot and Leeds said Tuesday that they are encouraging residents to learn how to identify browntail moth infestations and about the risks of exposure.

Dr. David Salko, a family medicine practitioner from Topsham Family Medicine, which is part of Central Maine Healthcare, said that he has already seen a number of cases of browntail moth exposure this year.

“On the onset, (it) appears to be worse than last year,” Salko said.

While the topical rashes caused by exposure to browntail caterpillars “can create a reasonable amount of misery,” it’s not particularly dangerous to most people and can be treated with over-the-counter medications and at-home remedies, such as a cold compress, Salko said.

He warned that those with asthma or other pulmonary conditions can experience severe asthmatic reactions if the browntail moth hairs are ingested.

“It’s definitely reasonable to reach out with any level of symptoms, especially if they’re persisting,” Salko said.

The browntail moth caterpillars are most active from mid-April to early October, though it’s difficult to say if their presence will abate any sooner than that, or when the outbreak phase will end.

“There’s no real crystal ball, unfortunately,” Kanoti said.

The Maine DACF has more information on how to identify and remove browntail moth nests and the Maine CDC has information on how to treat for exposure to the caterpillar.

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