🐛 Browntail Moth

🔍 Identification

Adults: 35-42mm wingspan; white wings with distinctive white-tufted brown abdomen tip (females). Caterpillars (damaging + toxic stage): 35-40mm; dark brown with two red spots on top near tail; covered in dense, barbed hairs. Winter webs: silky white tents at branch tips on cherry, oak, and birch — persisting through winter and into spring. Range: restricted to Maine and coastal Massachusetts (Cape Cod peninsula primarily).

🧬 Biology & Behavior

Browntail moth is an invasive from Europe established in New England in the late 1800s. The toxic hairs (setae) break off and become airborne — especially during spring caterpillar development and again in late summer when the hairs disperse. The microscopic barbs lodge in skin and lungs. Adults don't cause the rash — only caterpillar hairs do.

⚠️ Damage & Health Risk

Persistent contact dermatitis (poison-ivy-like rash) lasting 1-6 weeks from airborne or direct hair contact; respiratory irritation ranging from mild to severe in sensitive individuals; potential asthma exacerbation; eye irritation. Maine public health tracks exposure incidents annually.

🔧 DIY Treatment

Winter web removal (most effective): Cut infested branch tips with long-handled pruners in winter (January-April) and carefully bag. Don't shake the webs. Don't compost — bag and seal for trash. Spring caterpillar treatment: Bt kurstaki spray in May when caterpillars are small. Spinosad spray. Wear N95 mask and long sleeves during outdoor work in infested areas. Change clothes after outdoor activity in caterpillar season.

👷 When to Call a Pro

For large trees, professional spray applications by licensed arborists provide safer coverage than homeowner ladder work. Maine Forest Service provides guidance on large-scale management.

❓ FAQ