05/02/2024
Department of Health and Human Services
Maine Center for Disease Control and Prevention
286 Water Street
11 State House Station
Augusta, Maine 04333-0011
Tel: (207) 287-8016; Fax (207) 287-9058
TTY Users: Dial 711 (Maine Relay)
Maine Health Alert Network (HAN) System
PUBLIC HEALTH ADVISORY
To: All HAN recipients
From: Isaac Benowitz, State Epidemiologist, Maine CDC
Allison Kanoti, State Entomologist, Maine Forest Service
Subject: Health Risks from Browntail Moths
Date / Time: Thursday, May 2, 2024, at 11:15AM
Pages: 2
Priority: Normal
Message ID: 2024PHADV012
Health Risks from Browntail Moths
Background: The browntail moth is an invasive species of both forest and human health concern. Maine is the
only state in the U.S. currently experiencing widespread problems with this moth. The microscopic hairs found
on browntail moth caterpillars, shed skins, and cocoons can cause skin reactions and breathing problems.
Providers should be aware of the risk of browntail moth hairs, and the public should know what they can do to
help reduce exposure to browntail moth caterpillar hairs. Browntail moth caterpillars are hairy, dark brown
caterpillars with two red-orange dots on the back. Older caterpillars have two white stripes running from head
to tail.
Symptoms: Most individuals affected by the hairs develop a localized rash similar to poison ivy that will last
for a few hours up to several days. In more sensitive individuals, the rash can be severe and last for weeks.
Dislodged hairs can become airborne and cause trouble breathing, including respiratory distress, if inhaled.
Symptoms result from both a chemical reaction to a toxin in the hairs and a physical irritation as the barbed
hairs become embedded in the skin and airways.
Seasonality: Caterpillars are active from April to early July. Hairs from caterpillars, shed skins, and cocoons
can become airborne and settle on vegetation and other surfaces. They can be stirred up during mowing,
raking, sweeping, and other outdoor activities. Hairs remain toxic for 1-3 years in the environment but lose
their toxicity over time.
Maine Center for Disease Control and Prevention
2024PHADV012 – Health Risks from Browntail Moths 2
Browntail moth winter web with basking caterpillars (left), caterpillars (center) & cocoons (right)
Maine summary: The Maine Forest Service surveys indicate that most areas of Maine that have significant host
tree populations are at some risk for browntail moth infestation. Preferred host trees include apple, birch, cherry,
crabapple, oak, pear as well as other hardwoods. Every county in Maine has had at least some browntail moth
webs or caterpillars detected in them since 2022. In 2023, notable higher populations were seen in Cumberland,
Hancock, Knox, Penobscot, and Waldo counties.
Even in areas with browntail moth management, the risk to the public remains high due to the persistent nature
of the hairs. Visit the Interactive Browntail Moth Dashboard to see where the Maine Forest Service has noted
significant browntail moth activity in recent years. People may experience impacts even in areas with low or
undetected populations of browntail moths. Visit our browntail moth communications partners’ Knock Out
Browntail pages hosted by the Department of Agriculture, Conservation and Forestry for information on the
recognition, management, and mitigation of browntail moth impacts.
Information for providers:
• Be aware of the risk of browntail moth hairs, particularly in areas with known populations.
• There is no specific treatment for dermatitis due to browntail moths; treatment is focused on relieving
symptoms and eliminating ongoing exposure.
• Mild rashes may be treated with calamine or caladryl lotion, hydrocortisone cream, or taking a cool
bath with Aveeno Oatmeal. or baking soda. Severe reactions may require prescription medication.
• The toxin in the hairs is extremely stable and can remain a hazard for years.
Recommendations to reduce exposure:
• Avoid places heavily infested by caterpillars.
• Take cool showers and change clothes after any activity that may expose you to browntail moth hairs.
• Dry laundry inside during June and July to avoid having the hairs embedded in clothing.
• Wear a respirator, goggles, and coveralls tightly closed at the neck, wrists, and ankles when
performing activities that stir up caterpillar hairs such as mowing, raking, w**d whacking, and
removing pupal webbing.
o Perform these tasks on damp days or spray down vegetation with a hose. The moisture helps
keep the hairs from becoming airborne while working.
For more information:
• Contact 211 Maine for answers to frequently asked questions on browntail moths:
o Dial 211 (or 207-874-2211)
o Text your zip code to 898-211
• Maine CDC Browntail Moth Webpage: www.maine.gov/dhhs/browntailmoth
• Maine Department of Agriculture Conservation and Forestry Browntail Moth Webpage:
www.maine.gov/dacf/knockoutbtm
This page contains information on Browntail Moth.
