Yarmouth’s tree warden has a plan in place to combat the invasive browntail moth population this spring.

The browntail moth, which has hairs that can cause respiratory problems and a rash similar to poison ivy, infests many Maine towns from April to June, making it difficult for residents to enjoy the outdoors.

A browntail moth caterpillar.  Contributed / Maine CDC

“To have it in the town, especially during the summer months when people want to spend time outside, is not good,” said Scott Couture, a licensed arborist who was hired as town tree warden last June. “Young people and people with asthma are vulnerable to the effects of the browntail moth caterpillar.”

Couture has identified browntail moth nests in trees along downtown Main Street for removal. He also has mapped out areas around town where moth infestations would be most detrimental to people and will be monitoring those areas so nests that crop up there can be quickly removed.

“The town of Yarmouth is looking at only treating major walking routes on public properties that would be a spot to gather,” said Yarmouth Community Services Director Karyn MacNeill said. “So, under park benches, playgrounds, things like that.”

Yarmouth experienced the worst infestation of browntail moths of the last 10 years in 2018, MacNeill said. Since then, a combination of treatment and cold, damp spring seasons has kept the numbers from rising. This year, however, an increase in small pockets of nests has been spotted.


Couture estimates that the browntail moth population locally is only about 20% or 30% of what it was in 2018, but the nests still need to be removed. The town will contract out the removal, which involves a trunk injection of pesticides for trees close to the water and a root injection for other trees.

While the town takes care of populations in larger trees around public areas, Couture said it’s important for Yarmouth residents to know that they can get rid of nests on smaller trees themselves. The nests look like folded leaves, and are black and gray in color.

“Browntail moth caterpillars really like flowering crab apple trees, and the trees themselves are small,” Couture said. “People can actually cut the nests out themselves with a pair of clippers.”

Once the nests are removed from the trees, Couture advises submerging them in water, then either throwing them in the trash or burying them in the ground.

“Do not burn them,” Couture said. “The product that the caterpillar produces will then become aerosolized, and it can get into people’s lungs and cause problems.”

Even with eradication of the new nests, browntail moths can impact people’s routines throughout the spring and summer, MacNeill said. Mowing the lawn and other yardwork can be challenging because the caterpillar hairs can still present from the previous year.

“It could change people’s exercise routines,” MacNeill said. “People do change their course of outdoor activities due to the threat from browntail moths.”

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