Browntail Moth Management Overview

What can we do to reduce impacts from browntail moth?

Maine has persistent browntail moth populations that, even during periods of lower population, have caused human impacts every year over the last several decades. Browntail has been established in Maine since 1904 and has been in an outbreak phase over a broader area since 2015.

We cannot stop the spread or eliminate the pain and frustration caused by browntail moth. However, there are steps that can be taken to reduce the impacts to people in areas with the pest. This site provides resources for towns and other organizations considering taking actions to reduce impacts from browntail moth populations.

Bangor Maine Public Works Director Aaron Huotari provides DACF with a look into his department’s developing response to browntail moth populations in the city (January 2022).

Share your ideas on how to mitigate browntail moth impacts.

Education

Educating the public is the first step in managing browntail moth. All organizations engaged in responding to browntail moth are encouraged to provide education. Examples of how this has been done include providing information on websites and in social media, including inserts in utility bills and other town mailings, creating and displaying signs to warn of infestations.

Survey

Figuring out where browntail moth is in relation to human activities is an important part of deciding how to respond to its presence. Maine Forest Service surveys are coarse scale to assess state-wide populations. Finer scale surveys are necessary for local response and can play an important part of education, engaging others in your efforts and informing your management decisions.

Management

An integrated approach to managing browntail moth is the best approach to management. Management tools include mechanical, cultural and chemical control efforts. Some management approaches require a license, and others can be done by volunteers and unlicensed individuals. Some towns that have decided to engage in management request a public health nuisance declaration from Maine CDC.

Mechanical and cultural control efforts
Web clipping

Between mid-December and early April populations of browntail moth within reach can be reduced through clipping and destroying overwintering webs. Extreme populations and those in mature trees are not readily managed through this method. However, web clipping should be conducted where it is practical.

This activity may require work by a licensed arborist.

Several communities have organized grass-roots efforts to encourage web clipping including door knocking educational campaigns and equipment lending programs (for example through conservation commission, library or local non-profit).

Tree removal

Generally, this permanent solution is not recommended for trees that are otherwise providing important functions in the landscape and environment. Higher populations of browntail moth are temporary, tree removal is not. However, there are instances where tree removal may make sense. In general, we recommend tree removals targeting browntail moth take place when caterpillars are in their winter webs (October through March) and that webs are destroyed.

This activity may require work by a licensed arborist.

Restrict Access

In some cases, it may be possible to restrict access to an area in order to reduce exposure to caterpillar hairs. Consider installing signs warning of populations if other treatments cannot be done.

Adjusted Maintenance Schedule

Consider adjusting maintenance schedules for open areas around untreated infested trees. This will reduce both employee and public exposures, since use of unmown areas will be more limited.

Landscape design and planning

An important part of planning for browntail moth can be modifying the landscape around public use-areas so they are less inviting to the pest. Certain trees and shrubs harbor more browntail moth than others. Some have forms that lend themselves to browntail moth management by clipping from the ground, so need not be avoided, others pose a greater challenge to management. Careful consideration of artificial lighting so it is less attractive to insects and is not drawing moths closer to hosts can also play a role in designing or adapting landscapes. Although we do not generally recommend radical changes to established landscapes, potential effects from browntail moth should come into consideration when adding new elements to landscapes, altering established plantings or developing new landscapes.

Insecticide treatment: license required

In some cases, treatment with insecticides will be the best approach for balancing human use and browntail moth. We encourage people to work with licensed and experienced pesticide applicators. Except when you are treating your own private property with general use insecticides, all applications must be done by licensed pesticide applicators licensed in appropriate categories. There are special requirements for treatments in areas such as school grounds and other public spaces as well as for areas near marine waters.

Insecticide control methods can be broken into foliar applications and systemic applications.

Foliar application

Examples of foliar application include:

  • Treatment from the ground with truck-mounted mist blowers or hydraulic sprays. Some companies also apply hydraulic sprays from lifts
  • Treatment from the air using fixed wing or rotary aircraft

Systemic Application

Examples of systemic applications include:

  • Treatments with specialized tree injector systems
  • Treatments with capsules inserted in drilled holes
  • Treatments through soil or trunk applications

Municipal Battle Book

Communities considering broad-scale treatments may find this “battle book”, revised from products developed in the last outbreak, helpful:

Additonal Resources