Maine’s trees are already dealing with emerald ash borer, hemlock woolly adelgid, browntail moth and beech leaf disease. Several more pests are established in neighboring states and provinces. This page tracks them, so you can protect valuable trees before a new pest arrives.
Closest to arriving
Spotted lanternflyNot established in Maine. Found in almost 150 Massachusetts communities, with New Hampshire’s first field detection in Salem on August 25.[1] Adults are occasionally reported in Maine as hitchhikers on vehicles.[2]
Already in Maine
Emerald ash borerEstablished. Ash dieback and mortality were observed throughout southern Maine in 2026.[3]
Hemlock woolly adelgidEstablished. Widespread along the southern coast.[4]
Browntail mothEstablished. Found in all 16 counties; populations have been decreasing over the past couple of years.[5]
Beech leaf diseaseEstablished. Detected in 404 Maine towns as of July 2026.[6]
How we keep this list current
We check Maine Forest Service bulletins, state agriculture departments across New England, and university extension services every week, and update this page when a pest moves closer to Maine.
Why plan ahead?
The trees that survive a new pest are usually the ones that were protected before it arrived. Knowing which trees on your property are at risk, and removing invasive host plants like tree-of-heaven, gives you time to act. A tree health assessment is a good place to start.
Sources
- Boston Globe: Spotted lanternfly infestations in Massachusetts (September 2026)
- Maine DACF Horticulture Program: MELeaf newsletter, June 2026
- Maine Forest Service: Forest & shade tree conditions, August 2026
- Maine Forest Service: Hemlock woolly adelgid overview and distribution
- Maine CDC Health Advisory: Browntail moth (May 2026)
- Maine Forest Service: Forest & shade tree conditions, July 2026