February is Browntail Moth Awareness Month. The outbreak of BTMs has increased in 2021. Courtesy photo

SCARBOROUGH — The Maine Department of Agriculture, Conservation and Forestry (DACF) has named February Browntail Moth (BTM) Awareness Month.

According to Maine Forest Service State Entomologist Allison Kanoti, the outbreak of BTMs has increased in 2021 with almost 200,000 acres of damaged mapped in aerial surveys. Winter is the best time to spot an infestation and take steps towards controlling the caterpillars, she said.

“February 2022 has been recognized as Browntail Moth Awareness Month in Maine to encourage people to take advantage of the dormant season of the insect and join together to reduce impacts from browntail moth,” Kanoti said.

The Browntail Moth population in Maine was established in 1904, BTM populations in Maine have been in an outbreak phase since 2015 and the pest cannot be eradicated. The species is only found on the coast of Maine and Cape Cod, Massachusetts. The moths have settled in areas that have significant host tree populations like oak, apple, crabapple, pear, birch, cherry. These as well as other hardwoods are at risk of being infested by the caterpillars.

“Most areas of Maine, especially along the coast and inland, that have significant host tree populations are at risk,” Kanoti said. “In 2021, overwintering browntail moth webs were found in every county in Maine except York. The highest populations in 2021 were found in Androscoggin, Cumberland, Kennebec, Knox, Lincoln, Sagadahoc, and Waldo Counties, with some pockets of high populations in adjacent counties. Aerial surveys revealed intensification in many areas, and first damage was mapped in coastal Hancock County and Oxford County.”

Proper identification of BTM winter webs is very important, she said. The winter months are the best time to identify and remove the BTM winter nests from the trees on one’s property. Nests are commonly found in the tops of oak trees and in ornamental fruit trees. Colonies are enclosed within webbed nests of white silk tightly woven around a leaf in trees or shrubs. Nests are spun in early fall and contain 25 to 400 caterpillars, they remain attached to twigs or small branches through the winter and early spring. The nests are formed and occupied in summer and early fall by yellowish caterpillars with many tufts of long hairs and brown markings. Mid fall the caterpillars have left the nests and during the winter months the nests become detached and hang loosely from branches.

Those finding nests can use hand snips or extendable pole pruners to clip them from trees. Soak them in a solution of water and detergent for several days or burn them in an incinerator to kill the eggs and larvae. Arborists will be able to help those who need help identify Browntail Moth webs and can remove them from the tops of tall trees.

There are health concerns related to BTMs. The caterpillar’s microscopic toxic hairs can cause trouble breathing due to inhaling the hairs and can be very serious. Symptoms can last from a few hours up to several days, some sensitive individuals may get a rash that can be severe and last for several weeks. The rash results from both a chemical reaction to a toxin in the hairs and a physical irritation as the barbed hairs become embedded in the skin.

Although there is no way to stop the spread or eliminate the pain and frustration caused by BTM, there are ways to reduce the impact to people in areas where caterpillars are located. The best way to help is to make sure to clip and destroy the winter webs. Professionals can be hired to mitigate the problem. If you find a browntail moth in your neighborhood, let neighbors know and let town officials know.

For more information, visit the website https://www.maine.gov/dacf/knockoutbtm or contact Maine at 211 for answers to frequently asked questions on BTMs.