Browntail Moth Precautions

The browntail moth caterpillar has tiny (0.15 mm) poisonous hairs (setae) that cause dermatitis (skin rash) 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 from either being dislodged from the living or dead caterpillar or they come from cast skins when the caterpillar molts. Most people affected by the hairs develop a localized rash that will last for a few hours up to several days but on some sensitive individuals the rash can be severe and last for several weeks. The rash results from both a chemical reaction to a toxin in the setae and a physical irritation as the barbed setae become embedded in the skin. Respiratory distress from inhaling the hairs has been reported (11% of the population in one health survey) and can be serious.

The following precautions may help people living or visiting browntail moth infested areas during June through August:

  • Avoid places heavily infested by caterpillars. Campers should plan their stays on un-infested islands.
  • Take a cool shower and change clothes after any activity that might involve contact with browntail moth hairs.
  • Dry laundry inside during June and July to avoid having the hairs become impregnated in clothing.
  • Wear respirator, goggles and coveralls tightly closed at neck, wrists and ankles when performing activities that stir up caterpillar hairs such as:
    • mowing
    • raking
    • weed whacking
    • removing pupal webbing from eaves and boats.
  • Perform the above tasks above on damp days or wet down material with a hose as moisture helps keep the hairs from becoming airborne there by minimizing contact.
  • Use caution cleaning debris left by caterpillars because the toxin is extremely stable and remains a hazard for a number of years. Summer residents should bear this in mind when opening cottages that have been closed all winter as the hairs frequently settle over the winter and may be contacted when spring cleaning. Wet mopping prior to vacuuming or dusting is advised.
  • Consult your physician if you develop a severe reaction to the browntail moth.
  • Be aware that the chances of contacting browntail hairs increases during dry windy conditions.

Maine Forest Service - Forest Health and Monitoring Division

April 2008