BOWDOINHAM, ME – DECEMBER 1: Towns in Sagadahoc County discuss a regional approach to combat Brown Tail Moth, an invasive insect that defoliated more than 62,000 acres of trees this fall.Ellen Baum shows some of the moth larvae found in nests in the area. (Photo by John Ewing/Portland Portland Press Herald via Getty Images)
The troublesome -- and itch-inducing -- browntail moth caterpillar has been found in New Hampshire for the first time in 75 years, according to state officials.
Browntail moth caterpillar winter webs were recently located and removed at the Isles of Shoals off the New Hampshire coast, the New Hampshire Forest Health Bureau announced Monday.
“We’ve been monitoring an infestation of browntail moth over the last decade as it expanded to most of southern Maine,” said Kyle Lombard, administrator of the New Hampshire Division of Forests and Lands’ Forest Health Bureau. “While this first appearance in New Hampshire is offshore, now is the time for everyone to keep an eye out for these caterpillars because they can create uncomfortable and sometimes even dangerous health risks for some people.”
Browntail moth caterpillars have poisonous fine hairs that can produce skin rashes similar to poison ivy, even when the exposure is airborne. Inhaling the hairs can also cause serious respiratory issues in some individuals. Officials said people should not handle the caterpillars without wearing proper gloves and, when possible, a mask.
The caterpillars can be identified by their dark brown coloration, fuzzy appearance and two conspicuous red-orange dots on their tail end.
In New England, the moths' caterpillar stage lasts for nine months, from August to late June. But between April and July is when the risk of exposure to their hairs is greatest. After that, exposure to hairs that remain on surfaces can still occur but is less likely.
Oak and apple trees are the primary hosts for browntail moth caterpillars, but winter webs can also be found in coastal shrubs like beach plum and cherry. The winter webs are small, tight clumps on two or three leaves at the tip of a branch and tend to be enclosed in silk. They form in the fall and can be removed anytime between November and mid-April.
Native to Europe, the browntail moth was accidentally introduced to North America in the late 1800s, eventually spreading to all New England states, New Brunswick and Nova Scotia. Massive federal work projects in the 1920s and 1930s, in cooperation with biocontrol research, reduced the infestation area to a small region along the Maine coast. In 2022, it was found in more than 150,000 acres, mostly in the southern half of the state.
For more details about browntail moth caterpillars and to report any sightings, visit nhbugs.org.
