HARPSWELL — The town is expected to face another outbreak of browntail moth caterpillars this summer without the aid of most common pesticides used to kill the insects.

Last year’s infestation in Harpswell was moderate compared to Brunswick and Topsham, with the impact mostly isolated in three regions, according to Mary Ann Nahf, chairwoman of the Conservation Commission. 

Still, Nahf is urging residents to clip browntail nests from area trees and dunk them in soapy water to prevent the caterpillars from hatching in the spring – a proactive move that could reduce amount of airborne caterpillar hairs that can cause ugly rashes and respiratory problems.

“If you clip a nest now, you don’t have an insect there in the summer,” she said, adding each nest can contain 40-400 larvae.

Clipping is critical, Nahf said, given Harpswell’s strict pesticide ordinance. Coincidentally – and unwittingly – on the eve of the outbreak, the ordinance was modified last March to prohibit all pesticides within 25 feet of the shoreline.

Aerial spraying – an effective, yet controversial method that applies a mist of chemicals from above – is banned in town.

“The pesticides used to combat brown tail moths are toxic to shellfish,” Nahf said.

She said the town did some spraying in the late 1990s to fight the moths, “and then (fishermen) started finding dead lobsters.”

“And they didn’t resemble the dead lobsters they usually see – they looked healthy, they weren’t cannibalized,” she went on, noting that, as insects, lobsters can be killed by insecticides.

Last year, 35 residents applied for waivers to treat trees in their homes; with a permit, the ordinance allows licensed applicators to inject trees with some neonicotinoid pesticides. 

“I fully expect those same people who used it last year to come back again,” Nahf said.

She is worried, however, about local arborists and licensed applicators getting overwhelmed with the number of requests for services.

“That’s going to be a big issue,” she said, based on what she’s heard from arborists.

Brunswick and Topsham have organized on both the municipal and grassroots level to ready themselves for the anticipated spring outbreak – one that threatens to be triple the size of last summer.

Nahf isn’t as concerned about Harpswell, she said.

While their pesticide ordinance limits what the town and residents can do, she estimated that the infestation is contained to about 5 percent of the town, in three places: the end of Harpswell Neck, north Cundy’s Harbor, and near the Brunswick town line, by the Skolfield Shores Preserve.

Last summer, “I probably got two or three calls about (moths) from the public,” she said.

Callie Ferguson can be reached at 781-3661, ext. 100, or cferguson@theforecaster.net. Follow Callie on Twitter: @calliecferguson.

Skolfield Shores Preserve, along Route 123 at the Brunswick town line, is one of three places in Harpswell where an outbreak of browntail moth caterpillars occurred last summer. The town Conservation Commission is urging residents to act proactively by clipping nests to mitigate an anticipated infestation this spring.