Do you know the four Rs that "KNOCK OUT" Browntail Moth?

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Maine Forest Service

Do You Know the Four Rs to "KNOCK OUT"
Browntail Moth?


Knock Out BTM


Follow the Four Rs to Knock Out Browntail Moth

Browntail Moth Awareness Month is right around the corner in Maine! February is when our community is encouraged to take advantage of the dormant season of the insect and join together to "KNOCK OUT" Browntail Moth (BTM).

Winter is the best time to clip and destroy BTM winter webs within reach or hire licensed arborists or pesticide applicators to reduce out-of-reach populations. BTM populations in Maine have been in an outbreak phase since 2015, and the pest cannot be eradicated. While long-lasting tree defoliation and branch dieback are major concerns, BTM's microscopic, toxic hairs can cause trouble breathing and skin irritation similar to poison ivy from a few hours up to several weeks.

Follow the four Rs to reduce BTM populations on your property and protect your family and your community.


BTM Caterpillars in a line


Follow the Four Rs to "KNOCK OUT" Browntail Moth in Our Communities and Reduce the Itch!


Recognize BTM

Learn how to recognize if the trees where you live, work, and play have BTM. Their winter webs can look like single leaves hanging onto twigs or fist-sized clumps of leaves tied together tightly with silk. Winter webs are easiest to locate on sunny days, where the silk in the webs makes them "shine" in the sun. Knowing where the nests are in your yard or town can help inform your management decisions. Learn more by participating in the BTM Awareness Month events included below.

Recognize photo BTM 2

Webs can look like fist-sized clumps of leaves tied together tightly with silk or like single leaves hanging onto twigs.

Remove BTM

With permission, remove webs with hand snips or an extendable pole pruner in areas within reach of the ground and away from hazards such as powerlines. Protect your eyes and skin from hairs that might be present from past caterpillar activity. After removal, destroy webs:

  • Burn them safely and legally or
  • Soak them in soapy water for several days, then dispose of the webs in the trash.
Man using pruners on tree

Use hand snips or extendable pole pruners to remove webs within reach of the ground and away from hazards such as powerlines.

Recruit BTM

Winter is a great time to identify webs that may be too difficult to remove on your own. Recruit professional help to treat webs out of reach or near hazards on the property you own or manage. Licensed Professional Arborists can remove BTM webs in larger trees and shrubs in the winter. In trees where the caterpillars' hairs cause a nuisance and where it is not practical to remove the webs, Licensed Pesticide Applicators may be able to use insecticides during the growing season to manage BTM.

Browntail moth winter webs in large oak trees

In large, heavily infested trees like these oaks, removal of webs may not be practical because of the time and cost involved in this approach. In trees like this that are a concern from the standpoint of human health or nuisance, licensed pesticide applicators may be able to use insecticides to help reduce impacts from browntail moth.

Reach Out BTM

If you find BTM in your neighborhood, reach out and let your neighbors and town officials know. The more neighbors, businesses, and others that get together to respond to the problem, the better the results.

Hand holding a winter web, a line of cars in the background

Vehicles line the road at a community web-clipping event in Deer Isle. Foreground, browntail web in serviceberry. The more neighbors, businesses, and others that get together to respond to the problem, the better the results.

BTM Caterpillars in a line


Upcoming BTM Awareness Month Events

Everyone is invited to participate in the following BTM Awareness Month events or set up community events. Use #KnockOutBTM on social media to share your efforts this winter. Some ideas for activities include mapping infestations on the town and public properties, hosting public service web-clipping events, creating contests for the most webs clipped or other community, and knowledge building activities.


2023 Events:

January 31, 2023, 6:30 PM
Cost: Free
Location: St. George Town Office in Tenants Harbor and virtually
The St. George & South Thomaston Conservation Commissions is sponsoring an in-person and virtual educational event on how to spot Browntail Moth webs and Hemlock Woolly Adelgid masses in the winter and how to slow the spread of these insects. For more information or to participate by Zoom, please contact with "Invasive Pests" in the subject line.

February 2, 2023, 10:30 to 11:00 AM
Cost: Free
Location: Virtual
The Maine Forest Service is virtually hosting Entomologist Tom Schmeelk to kick off Browntail Moth Awareness Month. Webinar topics will include past and current history, and the four Rs that knock out Browntail Moth. More information is available on the MFS Events website. Anyone is welcome to attend and no registration is required.

February 8, 2023, 6:30 to 8:15 PM 
Cost: Free
Location: Virtual

The Southern Maine Volkssport Association (SMVA) is virtually hosting MFS Entomologist Tom Schmeelk for a webinar on the biology, history, life cycle, current situation, management and mitigation strategies for Browntail Moth. Pre-register via email by contacting Denise Macaronas at

February 2023
Cost: Free
Location: Your neighborhood!
Host your own neighborhood clipping event during Browntail Awareness Month! It's a great way to stay in touch with your community during the winter season, and it's an even better way to reduce BTM populations to protect you and your neighbors.


Knock Out BTM

For more information:

The Maine Forest Service (MFS) Forest Health and Monitoring Division coordinates within state government, local communities, and directly with citizens to respond to this issue. Comprehensive BTM information and tools compiled by MFS, Board of Pesticides Control, Maine Center for Disease Control, the University of Maine and other partners, including research, infestation tracking, FAQs, and educational resources for communities, municipalities, businesses, and healthcare providers, are available on the Maine Forest Service website.

For answers to Browntail Moth FAQs: