Browntail Moth Rash and Infestation: Get the Facts Now

The Browntail Moth has gained notoriety in recent years due to their population spikes, which have reached historic levels. The reason for heightened concern is that the toxic hairs shed by browntail moth caterpillars can cause severe rash or respiratory issues. The health threat is particularly challenging because the poisonous caterpillar hairs are easily airborne and encountered unknowingly. Even driving through an infested area in an open-air vehicle can lead to issues for sensitive individuals.

2024 Maine Browntail Moth Update

The Department of Forestry has spotted browntail moth caterpillar webs in all 16 Maine counties. The highest concentration continues along the coast, but the caterpillars move westward each year. Links to the most recent survey maps from the Maine Department of Agriculture, Conservation, and Forestry:

There are no 2024 maps at this time. Visit the Maine Forest Service’s news section for the most up-to-date information, or subscribe to updates from the Department of Agriculture, Conservation, and Forestry.

Weather Forecast

The weather plays a huge part in hair activity. Dry and windy weather sets the hairs in motion, while rainy weather keeps the hairs from becoming airborne. Continually wet conditions can also produce a fungus that kills the caterpillars (see below). Climate predictions from the National Weather Service indicate that this spring will be drier than last spring, with precipitation levels in the normal range. While this is great for outdoor activities, you’ll want to take precautions if you’re in areas of infestation.

The previous year also plays a role. A fungus (entomophaga aulicae) can develop in particularly wet springs, killing the caterpillars. Fewer caterpillars emerging from webs means they will not turn into moths that lay lots of eggs that hatch the following year. That is substantial since each moth lays 25-400 eggs. It’s too early to determine, however last year’s rain may reduce infestation in 2024.

Suffering from the Browntail Moth Caterpillar Rash?

Learn about your treatment options.

Browntail Moth Rash Spray and Lotion with Woman Scratching Arm

What causes the health issues of the Browntail Moth caterpillar?

Caterpillar rashes aren’t new or uncommon. Several caterpillar species contain poisonous hairs; fortunately, they have relatively benign health consequences. That said, they can cause significant discomfort. Throughout much of its life cycle, the moth sheds its toxic hairs, which become airborne or attach to leaves and brush. When the barbed hairs contact our skin or lungs, they can cause itchy, painful rashes or respiratory issues. Issues are reported most in June and July when the toxin concentration in mature larvae is at its highest.

Browntail Moth Life Cycle

Respiratory Issues

Respiratory issues are less common but can be particularly problematic for asthmatics. People with asthma should carry an inhaler when spending time outside, especially in windy conditions. In addition, especially sensitive individuals may want to wear a mask that covers their nose and mouth.

Hairs that get caught in the mucosal areas of the mouth or throat can cause burning, irritation, or itchiness. Taking liquid Benadryl may relieve symptoms, which helps counter the histamine reaction caused by the hairs. We encourage you to seek medical attention if symptoms progress.

Skin Reactions

The most common reaction occurs when the caterpillar’s poisonous hairs contact the skin. The contact can cause chemical reactions to the toxins and physical irritation when the hairs become embedded in the skin. The chemical reaction, dermatitis, produces a severe rash similar to poison ivy. Symptoms can begin immediately or several hours after exposure and last a few days or weeks.

Some people are unaffected by the toxins, while others have extreme reactions and discomfort. Unlike the oil of the poison ivy plant, the hairs are not likely to transfer to others through physical contact. Many patients report that the rash starts with one small area and spreads across larger areas. The spread can be caused by transferring the toxins by scratching affected areas or from continued exposure to the hairs in the environment.

Browntail Moth Rash Treatment

No antidote exists for the toxins, so treatment focuses on relieving symptoms and eliminating further exposure. Over-the-counter products are a good start for mild cases. Severe reactions may require prescription-strength topical therapies, oral steroids, or both. Please consult your doctor or urgent care clinic to determine the appropriate action.

Over-the-Counter Treatments

Although you can try a single product, you may need a combination of products to address the multiple symptoms of the browntail moth rash (itching, burning, pain, swelling, etc.). Below are two “recipes” for an over-the-counter version of our prescription-strength lotion and spray. Although not as strong as our compounded lotion, patients have communicated that they work well.

Since many reactions occur over weekends, seeing a doctor may not be immediately possible. In these cases, you may find relief by soaking in a warm bath and applying calamine lotion or antihistamine cream. Also, try the over-the-counter formulation below.

OTC Lotion

Combine equal parts of the following creams:

  • hydrocortisone 1%
  • diphenhydramine hydrochloride 2% and zinc acetate 0.1%
  • lidocaine 4%

OTC Spray

In a spray bottle, combine equal parts of the following cremes and fill the rest of the bottle with witch hazel.

  • hydrocortisone 1%
  • diphenhydramine hydrochloride 2% and zinc acetate 0.1%
  • lidocaine 4%
  • witch hazel

Prescription-Strength Treatments

Browntail Moth Rash Spray and Lotion with Woman Scratching Arm

We make a prescription-strength topical browntail moth medication that has significantly reduced many patients’ discomfort. The compound is available by prescription only in lotion and spray form. The spray is especially beneficial in treating these rashes because they are often painful to touch. A provider may also prescribe a course of oral corticosteroids for those with an acute case.

Prevention Tips

There are several actions you can take to reduce your exposure risk.

  • Avoid places that appear to be infested.
    Indicators include vacated nests and defoliated trees and shrubs.
  • Wear a respirator and protective eyewear and cover exposed areas of skin while landscaping.
    This is important on windy days or when performing activities that would stir up hairs such as lawnmowing or raking.
  • Wipe or rinse off lawn furniture before sitting in them.
  • Cover your skin and wear eyewear when driving through infested areas in an open-air vehicle.
  • Close your car windows when driving through an infested area.
  • Do yard work on damp days or spray the area you’re working in.
    Moisture will help keep the hairs from becoming airborne.
  • Blow window fans outward instead of inward.
    You may not get the benefit of the breeze, but it will pull hot air out and prevent hairs from coming in from outside.
  • Don’t dry laundry outside.
    Hairs can become embedded in clothes and cause reactions when you wear them.
  • Wash exposed clothes (not with unexposed clothes) after spending time in an infested area to remove embedded hairs.
  • Take a long cool shower after spending time in an infested area.
  • Use duct tape to remove any hairs that may have embedded while outside.

Infestation Reduction

The best way to avoid the health repercussions is to remove the threat. Here are some tips:

  • Remove nests.
    Remove winter webs in winter or early spring, while the larvae are dormant. Many nests are too high for the average person to remove, so check with an arborist to see if they offer nest removal service. View a list of licensed arborists willing to prune winter nests or a list of licensed pesticide applicators willing to treat browntail moth.
  • Reduce outdoor lighting in late summer/early fall.
    Like other moths, adult browntail moths are highly attracted to light. Avoid attracting these pests to your yard, where they will lay eggs and cause further problems.
  • Talk to a Pest Solution Expert
    If you have them on your property, you can take action to address them. Even if you’re not fond of pesticides, there are options that are safe for trees and reduce the risk of human and animal exposure. You can find options by Googling “browntail moth removal.”

How do you know they’re in the area?

Browntail Moth Nest - Photo courtesy of Wikimedia Commons should be especially observant in the southern coastal part of the state, however, infestation continues to increase.

Their nests are noticeable webs that are typically found in oak or apple trees. They appear in the fall and shelter the larvae through winter. In spring, hundreds of larvae can emerge from each nest to start wreaking havoc on trees and humans.

The best indicators of browntail moth infestation are vacated nests and trees and shrubs with a lot of missing leaves. It’s also common to see browntail moth caterpillars laying on the ground after falling from trees. In fact, if you’re in an infested area, be very careful not to swat at something that has fallen on you. We’ve seen many people come in with a large swath of rash where they smashed and dragged a hairy caterpillar across their skin. It’s not pretty.

Frequently Asked Questions

How long does the browntail moth caterpillar rash last?

Depending on your sensitivity to the toxins, the rash can last a day or several weeks.

What does the browntail moth look like?

The moth is white with a brown tail. You’ll typically start to see them in late summer.
Adult euproctis chrysorrhoea -browntail moth

What does the browntail moth caterpillar look like?

The caterpillar is brown and white with tell-tale orange dots on its back. It has long reddish brown hairs protruding from its sides and back.

Browntail Moth Caterpillar on Leaf

Can you get a rash from the adult moth?

Not likely. The caterpillars are the ones that carry the poisonous hairs.

What browntail moth rash treatments actually work?

The rash has multiple symptoms that you may need to treat with multiple products. The severity level also varies wildly. While some have very mild reactions, others have intense reactions leading to lost sleep and work. While it’s impossible to guarantee results, we’ve heard great things about both OTC and prescription solutions. It all depends on your level of discomfort and how well your body responds to the treatment method. OTC and prescription-strength medications include hydrocortisone, lidocaine, and diphenhydramine. Calamine lotion, witch hazel and oatmeal baths, bars, and lotions also can provide relief. If you’re losing sleep, you may want to consider taking diphenhydramine (Benadryl) orally.

Do browntail moths bite?

No. In general, moths lack the proper mouthparts for biting. If you have a reaction to a moth or moth larvae, it’s most likely due to chemicals/toxins present on their bodies.

Does insurance cover the cost of your compounded solutions?

We are not contracted with insurance companies, however, we can provide a universal claim form for you to submit to your insurance company.

Can I use your compounded browntail moth solutions for other rashes?

Yes. Although we named them after the browntail pestilence, they can be used for many other types of dermatitis and contact rashes.

Resources and More Information

About the Author

Kim Crabb

Coastal Pharmacy & Wellness Staff

Kim is the marketing director at Coastal Pharmacy & Wellness and has been in the pursuit of wellness for decades. She led a workplace wellness program for over 12 years where she discovered that she loved helping people make positive healthy changes. You can often find her mired in information rabbit holes while researching answers to seemingly straightforward questions. It's ok; she loves it because it means she can share new-found knowledge with lovely people like yourself!


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