Homestead
BDN’s Homestead section is a celebration of rural life. Our writers cover small farms, animals, DIY solutions and fascinating Maine people who find unique ways to live simply. Read more Homestead stories here.
The caterpillars of browntail moths, and the rash-causing poisonous hairs they spread, are back for the season in the Bangor area.
The invasive caterpillars emerged at state monitoring sites in Bangor and Newport at the end of April, according to the Maine Forest Service’s first seasonal update for the year.
That’s the latest recorded appearance since the state started monitoring sites weekly five years ago. It’s likely because of colder temperatures this year, which can signal to insects that there’s a risk of frost and that new leaf buds aren’t available for food, according to the service.
Populations have steeply declined since the caterpillars’ 2022 peak made working outside in central and coastal Maine riskier and itchier, but the caterpillars haven’t disappeared. And because of boom-and-bust cycles in population, they’ll likely be back en force – one day.
Microscopic, poisonous hairs from the caterpillars can cause itchy rashes or breathing problems when people come in contact with them. In Maine, they feed on oak, apple, cherry, crabapple, elm, birch and poplar trees, according to the forest service, along with shadbush, and rugosa rose bushes.
The caterpillars affected more than 150,000 acres in 2022, according to state data, an estimate that dropped by more than half the next year. In 2024 and 2025, fewer than 5,000 acres were affected.
Webs decreased across much of the state this winter, according to the service, which ultimately chose monitoring sites for the year in Bangor, Bridgton, Newport and Turner.
Insect populations can grow until they collapse and then start to grow again, the state has said. Previous rainy conditions also likely helped the spread of pathogens that affect browntail moths in particular.
“The browntail moth will always be present to some extent in Maine’s forests, and we expect the populations to increase again,” the service said in a December 2025 update.
The state recommends showering after working near infested areas and keeping outdoor lights off in July to avoid attracting the moths. Webs can also be clipped in the winter, and trees can also be treated with pesticides.
