Browntail Moth Update #2: April 28, 2023

View as a webpage  /  Share

Maine Forest Service

Browntail Moth Update #2: April 28, 2023

This week, we observed browntail caterpillar emergence at all of our monitoring sites. It should be noted that although emergence was seen at every site, not every web has had caterpillar emergence. This is likely because of the recent rainy weather we’ve been experiencing across the state. Rainy spring weather is a great start for an epizootic outbreak of the pathogens (fungal and viral) that attack browntail caterpillars. Although it is still a bit early for the fungus and virus to have a huge impact on the caterpillars, we welcome the coming rain. Rain is also very beneficial to the health of the host trees since the state has had relatively dry spring weather the past few years. These rain events will help invigorate host trees and allow them to tolerate some of the defoliation they will experience. 


BTM bud feeding

Browntail caterpillars feeding on newly emerging spring buds in Skowhegan 2023.

At most sites, we observed that many host plants (oaks, apple, cherry, crabapple, elm, birch, poplar, shadbush, and rugosa rose) had newly emerged leaves, which make nutritious meals for the young browntail caterpillars. Even though they are small, their hairs readily break off and can cause an irritating rash to areas of exposed skin. Please plan ahead to avoid exposure to hairs and treating symptoms related to exposure.


BTM ellsworth

Browntail caterpillars have emerged from their winter webs at all of the 2023 monitoring sites. Caterpillars are now beginning to expand their webs by producing silk.

Browntail have begun producing silk to expand their winter webs. Eastern tent caterpillars are also out now and beginning to create their silk tents, too. 

Browntail Moth Mitigation Fund – Update 

The Browntail Moth Mitigation Fund was established by the legislature and signed into law last year. The fund was established for government entities or non-profit organizations in areas with significant browntail populations to reduce impacts from browntail moth. Upon request by an applicant, the division, in its sole discretion, may decide to add additional areas to the division’s list of eligible areas. The rules for this fund have been finalized, and the request for applications (RFA) is now available. Only applications from government entities or non-profit organizations will be considered; funding is not available for individuals. Look for continuing updates in this bulletin and also on the Division of Procurement Services Grant RFP/RFA page.

For more information contact us at 

Learn More about BTM