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Browntail Moth Update #1: April 30, 2025m
Maine Department of Agriculture, Conservation and Forestry sent this bulletin at 04/30/2025 09:19 AM EDT
Every spring, the Forest Health & Monitoring staff conduct weekly site visits to areas with browntail moth (BTM) caterpillars to document their growth and keep an eye out for disease outbreaks. In 2025, our monitoring sites are Belfast, Brewer, Brigton, Dover-Foxcroft, Ellsworth, Harpswell, Newport, Old Town, Turner, and Unity.
On April 24, we documented BTM caterpillar emergence in our Brewer and Ellsworth sites. This week, we’ve confirmed emergence at all of our other monitoring sites.
As we start to see more sunny weather, BTM caterpillars will bask in the warmth and begin feeding on the new leaf buds of their host trees. Although the caterpillars are currently small in size, they can be recognized by their hairy appearance with red-orange dots on their back. Their hairs can break off and cause a rash to areas of exposed skin – take care to observe trees on your property or community to avoid the caterpillars.
Image: Newly emerged browntail moth caterpillars bask on their winter web during a sunny day in Brewer. Note the presence of two red-orange dots on the caterpillars, indicative of young browntail.
Aerial surveys in 2024 documented reduced defoliation acreage compared to previous years, suggesting BTM populations may be collapsing. However, 2025 winter web surveys revealed notable higher populations in portions of Androscoggin, Cumberland, Franklin, Hancock, and Oxford Counties.
In areas with a history of infestation or with an active infestation, please plan aheadto avoid exposure to hairs:
Avoid areas with BTM caterpillars,
Cover bare skin when working outside in infested areas (long sleeves, hat, gloves, closed-toed shoes, etc.),
Plan to do yardwork on wet days to reduce the hairs getting stirred up from mowing or raking leaves,
Take cool showers and change clothes after outdoor activities.
UPDATED: 2025 Browntail Moth Interactive Map
We have updated our interactive BTM map with winter web data from this past winter and aerial survey data from last year. This map can be used to better understand the possible impacts of BTM in your area, however, please be aware that it is not exhaustive. These are broad-scale surveys that do not completely cover the impacted areas.
