The Browntail Moth is spreading. Here is what you need to know.

The Facts

Source: State of Maine Department of Health and Human Services

The Browntail moth is an invasive species found along the coastal regions of Maine. This moth is an insect of both forest and human health concerns.

The browntail moth caterpillar has tiny poisonous hairs that cause dermatitis, similar to poison ivy on sensitive individuals. People may develop dermatitis from direct contact with the caterpillar or indirectly from contact with airborne hairs. The hairs become airborne in a few ways. Either being dislodged from the body of the caterpillar or they come from cast skins with the caterpillar molts. Most people affected by the hairs will develop a rash  That sometimes can be severe and uncomfortable. Some sensitive people can have a severe lasting for several weeks. A chemical reaction occurs from the toxin within the hairs—also, physical irritation in the skin. Respiratory distress from inhalation can be severe.

Caterpillars are active from April to late June. Hairs remain toxic throughout the summer but get washed into the soil and are less of a problem over time.

Where is it currently?

  • This pest has moved along the coast.  Starting in the Southern parts of the state working northerly. Some of the harder-hit areas this year seemed to be again Camden Lincolnville, Rockport area and now further up into Deer Isle. There have been nests seen further in off the coast. The old town, Newburgh and Unity areas too!! These caterpillars can travel from place to place on your vehicle, clothing or items carried. 

What time of the season am I at risk?

  • The highest risk period is from April – July.
    • The hairs are what contain the toxin.
    • The toxin within the hairs can be stable in our environment for up to 3 years, and the strands can become airborne at any time.
    • It’s essential to take precautions year-round if you are within a heavily infested area.

What are the symptoms?

  • A red bumpy skin rash can occur, causing itching and discomfort potentially for weeks.
  • Respiratory issues can occur if hairs get inhaled. People with respiratory issues asthma and such can have severe reactions when breathing in the hairs. If you have trouble breathing, swallowing, or swelling in your mouth, call 9-1-1.

Are my trees at risk as well?

  • Most definitely. These caterpillars feed on the leaves of these trees and can completely defoliate them within a short time.  

What happens if I don’t do anything to protect my surrounding trees?

  • If complete defoliation occurs for more than two years, any buildings and people are at risk of the tree dying and eventually falling.
  • If untreated, the caterpillars will continue to return each season and spread their toxic hairs in your yard.

What treatments are available to protect people around my home if I have an infestation in my trees?

  • Protect yourself by wearing long sleeve clothing, pants, and even dust masks and safety glasses, especially when mowing lawns.
  • These caterpillars primarily nest in Oak trees. Since these trees are typically vast and tall, treatment options become limited. Spraying foliage is often not recommended due to proximity to water and drift due to the height required to treat.  
  • Currently, options range from foliar treatments, tree removal (expensive), and injections.

That sounds expensive. Is there anything cost-effective?

  • YES! Injections are the safest method of management and the most effective when timed correctly.  
  • Timing for injection is based on the life cycle of this pest, and the time it takes for the injection to be absorbed.  
  • Yes, injections are directly into the infested tree. The tree will move the treatment, through the entire tree, and into the foliage. Once caterpillars are present, they will feed briefly on the leaves and ingest the material that is within the leaves and perish. 

Where can I find more information on treatment, cost and timing?

Please contact Ground Renovators Tree Healthcare. 

There is some information that explains the process of the injections. Sign up on the website for an estimate or call at your convenience. 207 949 4308

We offer many other services also. If there is something specific that you are looking for for your trees or ornamental gardens please don’t hesitate to contact us. We are able to diagnose diseases, insect problems and help with soil issues to give you the most out of your plant investment.

Thank you, 

Derek Legasse Owner

Ground Renovators LLC


  1. Kris Omicioli

    We spoke yesterday. 78 N Shore Lane in Winthrop. Brown tail moth.
    Please let me know if you can apply for the treatment in the next two weeks.

  2. Caron Foren

    Litchfield Maine is infested with these brown moth caterpillars. Started with a few years ago. 2021 I have killed at least a thousand of these. My oak and apple trees are full and I can hear their poop hit the ground like it is hail. My son has a terrible rash and I am having respiratory difficulties. I would like to learn more about injections. Thanks!!


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