As browntail moths build their winter nests, communities across central Maine are taking a variety of steps to combat the spread of a pest that has damaged trees and raised health concerns for people as it moves inland from the coast.

Waterville officials are preparing to launch a plan that includes removing nests, spring tree injections and leaf treatment.

The city earlier received approval from the Maine Center for Disease Control & Prevention to declare the moth a public nuisance, which allows the city to spend public money on both public and private property, with permission from private landowners, and advocate for state-level action and resources for municipalities.

Waterville City Councilor Thomas Klepach, a faculty member in the biology department at Colby College, urged city officials in June to take steps to curtail the growing infestation. Councilors a few days later declared a public emergency and the need to preserve the public health and safety of residents.

They authorized City Manager Steve Daly to spend up to $5,000 on a campaign to notify residents of the severity of the infestation. Klepach in July presented the city with a browntail moth mitigation plan.

Microscopic, poisonous hairs shed by browntail moth caterpillars can result in rashes similar to those caused by poison ivy, and people who inhale the hairs can develop respiratory problems. Klepach recommended, and the city agreed, to allocate $100,000 a year in the municipal budget for mitigation efforts.


Part of Waterville’s efforts is compiling a survey of residents to determine where the moth is nesting, areas of infestation and to collect other data.

“It’s sort of like taking a public observation inventory,” Daly said.

Augusta Community Services Director Earl Kingsbury said the city is taking a two-pronged approach to control the spread. Over the winter workers will cut nests from trees on city-owned property.

“We can’t really take care of anything on private property,” Kingsbury said. “But what we can do is get a package together with all the resources available and from the Maine Forestry Service and get that to every individual household in the city.”

A browntail moth caterpillar is shown June 2 between Jameson Dow, left, and classmate Charlie Ferris, both 10, in a tree at Ferris’s home in Waterville. The caterpillar, which has two distinctive reddish dots, has poisonous hairs that can cause a rash if exposed to skin. Officials across central Maine are priming their attack plans as the infestation of the moth is expected to continue in the coming years. Rich Abrahamson/Morning Sentinel file

In the last couple of years, dry, warm springs have boosted the population of the invasive insect, which has been moving into central Maine and taking hold on oak, maple and other broad-leafed trees.

“We’re hoping for a wet, cold, dreary spring,” Kingsbury said. “That may create a fungus in some of the nests and kill them before they even hatch.”


Kingsbury said when spring comes Augusta plans to inject insecticide into trees that haven’t been pruned. One employee is currently licensed for that work and three more are in training. If that’s not enough, the city has a tree service on contract it can call.

Gardiner acting City Manager Anne Davis this year called a halt to curbside pickup of brush and leaves, limiting the possibility of inadvertently exposing unaffected trees to infested brush.

Davis told the Gardiner City Council earlier this month that now is the time to take action against the caterpillar by getting rid of the nests.

“A lot of towns are hiring people to do this,” she said. “It’s not something our buildings and grounds people can do; it’s throughout the city.”


William Buckley, an arborist for Bartlett Tree Experts, which has been working with Waterville, says arborists in the state are busy working to eradicate the browntail moth.


Cotey Green, a certified Maine arborist who works for Bartlett Tree Experts, sprays an application to suppress browntail moth caterpillars on a red oak tree in Waterville recently. Photo courtesy of Bartlett Tree Experts

“It’s spreading very fast and you’re seeing higher populations in more areas, because we haven’t been having spring production of fungus to kill it naturally,” Buckley said.

Bartlett, based in Scarborough, focuses on larger trees such as oak using injections into trees and also by treating leaves, according to Buckley. Nest removal and pruning is a mitigation tactic that also works, especially in smaller trees including apple, crabapple and birch, and Bartlett works with smaller tree companies that do such work.

Bartlett focuses its efforts in places where people spend a lot of time such as public roadways. The moth tends to travel quickly in fields and along waterways, including the Kennebec River in Waterville and Augusta, according to Buckley.

“The tree is going to be highly impacted potentially forever, but it’s the impact on the people that we want to focus on eliminating,” he said.

State Entomologist Allison Kanoti said it’s difficult to determine how the infestation will look in three, five or 10 years in Maine because outbreaks are thought to build and then be brought to collapse by any number of outside factors.

“If the last 27 years are a useful guide,” she said by email, “we know that some areas in Maine will continue to experience heavy populations, with lingering higher populations seen especially in coastal areas after the collapse of the broader outbreak. Unfortunately, weeks like this should remind us that this problem is likely to worsen with continued climate change.”


She noted that there’s currently no state money available to assist private property owners looking to remove nests.


Browntail moths were first introduced in Somerville, Massachusetts, from Europe more than 100 years ago, but have become more prevalent in Maine in recent years. Severe drought conditions in summer 2020 were a boon for the caterpillar as populations along the Maine coast expanded into Waldo, Kennebec and Somerset counties.

In Waterville, browntail moth caterpillars became more noticeable this past spring. Daly reported several Public Works employees developed rashes from working in the city’s parks and ballfields, and from trimming greenery on roadsides. The moths typically infest oak, pear and apple trees, but also will eat birch, maple and other hardwoods and shrubs when preferred sources have been defoliated, according to Klepach, the city councilor.

Warning signs are posted at the entrances to city parks, playgrounds and school properties.

“We want to work with the school district to handle this — we haven’t formed that partnership yet, even though it’s one entity,” Daly said. “Those are the places where children are at highest risk, and people going there don’t expect to be threatened by anything, so we’re trying to create a safer environment than we had this past summer.”

Klepach says Waterville, and Maine in general, have not faced an outbreak of the magnitude they faced earlier this year in more than a century. Data gathered by the Maine Forest Service indicates the outbreak this year was in “a year-over-year exponential-growth phase,” he said.

Kennebec Journal staff writer Jessica Lowell contributed to this report.

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