Maine is experiencing a Browntail Moth (BTM) outbreak. They have been in Maine since 1904 and have been in an outbreak phase over a broad area since 2015. The caterpillars are found in patches along the Maine coast and more than 60 miles inland from the western Maine border to the New Brunswick border, with the greatest concentrations in mid-coastal Maine and the capital region.
Now through late June is the height of BTM caterpillar season and they have become expert hitchhikers. The Maine Forest Service is asking people to check their cars, trucks, boats, bikes, ATVs, and other vehicles for wandering BTM caterpillars. When they catch a ride, BTM caterpillars can set up housekeeping a new area.
If a BTM caterpillar is discovered before leaving an already infested area, it may be left on-site or destroyed. Never touch a BTM caterpillar with bare hands. If found after leaving the infested area, the caterpillar should be killed by putting it into a plastic bag or another container, freeze them or soak them in a bucket of soapy water before disposing of them in the trash.
BTM are a threat to a variety of trees and shrubs such as oak, shadbush, apple, cherry, beach plum, and rugosa rose. They are also a threat to humans. Their hairs can cause a red itchy rash. Symptoms can last anywhere from a few hours to several weeks and can be severe in some individuals. They can also cause respiratory issues if the caterpillar hairs are inhaled. If you are having difficulty breathing, swallowing, or have swelling on your mouth, tongue or throat, call 9-1-1.
The rash can be treated with baking soda paste, Calamine or Caladryl lotion or Hydrocortisone cream used sparingly on the itchiest areas. See your health care provider if home remedies are not working. Eating fruits and vegetables that may have been exposed could be problematic and such produce should be thoroughly rinsed or peeled.
If you wish to remove caterpillars from decks, buildings, driveways and other surfaces do it in a way that will not increase your risk of exposure to their hairs (No leaf blowers allowed). You can dislodge them from out-of- reach areas with a strong jet of water. To remove them more permanently, add a couple of inches of soapy water to the canister of a wet/dry vacuum, vacuum them up, and allow them to sit until the caterpillars have drowned. Then safely dispose of the contents in the trash.
Management through insecticide treatment should already be made as treatment for browntail should be completed before the end of May to limit buildup of toxic caterpillar hairs and host foliage loss. The Maine Forest Service recommends working with a licensed pesticide applicator for insecticide treatments.
Contact 211 Maine for answers to frequently asked questions on browntail moths, or contact Maine Center for Disease Control (Maine CDC) and Prevention at 1-800-821-5821.