Browntail moth caterpillars shed microscopic, barbed hairs that embed in skin and release a toxin — producing a rash similar to poison ivy. You don’t need to touch a caterpillar to be affected: the hairs become airborne and can remain toxic in the environment for up to three years. Most people develop a localized rash lasting a few hours to several days; sensitive individuals may experience a severe rash lasting weeks.
About the Rash
Browntail moth populations remain low in 2026
Maine Forest Service preliminary winter web surveys indicate trace to low amounts of webs across most of southern Maine, with moderate activity in southern Penobscot and Hancock Counties, and elevated levels around Sebago Lake in Cumberland County. Overall, populations are expected to remain well below the 2022 peak statewide — though localized nuisance populations will persist in some neighborhoods.
This continues a multi-year decline: defoliation dropped from 56,000 acres in 2022 to approximately 2,800 acres in 2024, driven largely by naturally occurring fungal pathogens that thrive in wet spring conditions. The full 2026 winter web survey will be posted to the Maine Forest Service website when completed.
Important: Even in low-population years, toxic hairs that have settled into lawns, leaf litter, and outdoor surfaces from prior years can still cause rash. Hairs remain toxic for up to three years. Take precautions in any area that has had activity in recent seasons.
About the Rash
What does browntail moth rash look and feel like?
Symptoms can begin immediately after exposure or appear several hours later, making it difficult to pinpoint the source. The chemical reaction that causes dermatitis from the toxin often presents similarly to poison ivy, though the hairs also cause physical irritation as they embed in the skin.
Primary symptom
Intense itching
Sensation
Burning & swelling
Spreads by
Scratching affected areas
Appearance
Red raised welts
Duration
Hours to weeks
Respiratory
Possible if inhaled
Unlike poison ivy oil, the hairs are not transferred person-to-person through physical contact. Many people report the rash starting in one small area and spreading — this is typically caused by transferring the toxin by scratching, or from continued exposure to hairs in the environment.
Respiratory symptoms are less common but can be serious, particularly for people with asthma. Hairs that reach the mucosal areas of the mouth or throat can cause burning and irritation. If you are having difficulty breathing or have swelling of the face, mouth, or throat, seek emergency medical care immediately.
About the Rash
Treatment Options for Browntail Moth Rash
There is no antidote for the toxin. Treatment focuses on relieving symptoms – itching, burning, swelling – and preventing further exposure. The right approach depends on the severity of your reaction.
Prescription-strength compounded spray & lotion
We formulate browntail moth rash spray and lotion in-house. Many area providers are already familiar. OTC kits are also available without a prescription.
Learn about treatment options.
For mild reactions
- Hydrocortisone 1% cream
- Diphenhydramine (Benadryl) – oral or topical
- Calamine lotion
- Colloidal oatmeal bath or compress
- Cool shower; avoid heat and hot water
- Non-scented moisturizer applied several times daily
For moderate to severe reactions
- Prescription-strength compounded topical – spray or lotion
- Oral corticosteroids (provider must prescribe)
- Consult your doctor or urgent care
- If breathing is affected — seek emergency care
About the Rash
Reducing your exposure risk
- Avoid infested areas during peak season. Vacated nests and heavily defoliated trees or shrubs are indicators of infestation.
- Cover up when landscaping. Wear a respirator, protective eyewear, long sleeves, and gloves — especially on dry, windy days or when mowing, raking, or doing any activity that stirs up debris.
- Work on damp days. Moisture keeps hairs from becoming airborne. Spray down the area before working if needed.
- Don’t dry laundry outside during June and July. Hairs embed in fabric and cause reactions when worn.
- Wipe down outdoor furniture before sitting. Hairs settle on surfaces and can transfer to skin on contact.
- Blow window fans outward. This prevents hairs from being drawn inside while still ventilating.
- Close car windows when driving through infested areas.
- Shower and change clothes after time spent in an infested area. Use cool water.
- Use duct tape to remove embedded hairs from skin before showering.
About the Rash
How to identify and reduce infestation on your property
The best time to act is during the dormant season, before caterpillars emerge in mid-April. Winter webs — silky, tightly woven nests typically found in oak, apple, or cherry trees — are the primary target.
- Remove winter webs between October and mid-April while larvae are dormant. Webs removed after caterpillars emerge are ineffective. For high webs, hire a licensed arborist.
- Reduce outdoor lighting in late summer. Adult moths are highly attracted to light and will lay eggs near your home if drawn in.
- Consider pesticide treatment before end of May. Licensed applicators offer tree injection and low-level spray options. Contact a pest control professional — treatment timing is critical and the window is narrow.
For a list of licensed arborists and pesticide applicators willing to treat browntail moth, visit the Maine Forest Service browntail moth page.
About the Rash
Common questions about browntail moth rash
Depending on your sensitivity to the toxins, the rash can last a day or several weeks.
The moth is white with a brown tail. You’ll typically start to see them in late summer.
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.
Not likely. The caterpillars are the ones that carry the poisonous hairs.
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.
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.
We are not contracted with insurance companies, however, we can provide a universal claim form for you to submit to your insurance company.
Yes. Although we named them after the browntail moth rash, they can be used for many other types of dermatitis and contact rashes.
About the Rash
Maine State Resources
- 2025 Browntail Moth Winter Web Survey (PDF)
- 2025 Browntail Moth Summer Aerial Detection Survey (PDF)
- Maine DACF Interactive Aerial Survey Map
- Maine: Forest Health Conditions Highlights in 2025: Report to the USDA Forest Service (PDF) – see page 6 for BTM information
Suffering from browntail moth rash?
Coastal Pharmacy & Wellness compounds prescription-strength rash spray and lotion in-house. We also carry OTC kits that ship same-day. Your provider can call or fax us directly — many area providers are already familiar with our formulations.
Pharmacy hours: Mon – Fri 9 am – 6 pm · Sat 9 am – noon
29 Marginal Way, Suite 4 · Portland, Maine