The Maine Department of Agriculture, Conservation and Forestry issued a reminder to kill browntail moths during the winter when they’re cocooned on the ends of tree branches before they become active and harmful when warmer weather arrives. Times Record file photo

BATH — The State of Maine Department of Agriculture, Conservation and Forestry issued a reminder on Monday that winter is the best time to mitigate browntail moths, an insect known to cause skin irritation that threatens large swaths of Maine.

Browntail moth caterpillars spend the winter cocooned in silken wrapped leaves on the tips of hardwood branches, especially oak and fruit trees. If found, the state advises clipping the cocoon off the tree and destroying it by leaving it in a bucket of soapy water overnight. The caterpillars become active again by mid-April when the weather warms.

The browntail moth can cause serious damage through defoliation, though the browntail moth has the added feature of being covered with hundreds of tiny, barbed poisonous hairs in their caterpillar stage. The hairs can cause rashes like poison ivy when they come into contact with skin, and if inhaled can cause respiratory issues.

The species was accidentally introduced into Somerville, Massachusetts from Europe in 1897. By 1913, the insect had spread to all of the New England states and New Brunswick and Nova Scotia. The species was decreasing until the 1960s when it was limited to Cape Cod and a few islands in Casco Bay, but populations are building again in Maine and are found in patches from the western Maine border to east of the Penobscot River, according to the Department of Agriculture, Conservation and Forestry.

Bath, which is particularly at risk alongside neighboring towns in the Midcoast, previously tried to eradicate the insect by injected trees with chemicals that repel browntail moths. The city also released 700 parasitic flies that prey on winter moths, but browntail moths were not affected, as they have no natural predator, meaning humans are left with the task of reducing the population.

State Entomologist Colleen Teerling told a Times Record reporter last year that while the browntail moth is a major issue in the Bath area, it’s far less widespread in New England than the winter moth, which means there are fewer resources working towards solutions to the hairy fiend.

“It’s a big problem for Maine, but outside of Maine nobody’s ever heard of it,” said Teerling. “There’s just no funding for it.”