Browntail moth- — an invasive species whose caterpillars have toxic, irritating hairs — is found at varying population densities over more than 6,500 square miles of Maine; see a map at maine.gov/dacf/mfs/forest_health/invasive_threats/browntail_moth_info.htm. It is a pest that has hunkered down in the Midcoast and Casco Bay area for years, and has recently expanded its footprint.
People looking to reduce browntail moth populations may look at the cocoons as an opportunity for reduction. However, one will have limited impact through cleaning cocoons. Safer, more effective control will be had through targeting larvae, either in overwintering webs (put a reminder in the calendar now to look for those structures at the tips of host branches around a property this fall and winter!) or as they feed on host leaves in early spring.
One may still want to remove the cocoons to limit potential for exposure to the toxic hairs they contain. However, do this with extreme caution. Cocoons are full of the hairs that can cause a rash or worse.
If planning to remove cocoons:
• Wear protective clothing; in addition to long sleeves, pants, socks, shoes, gloves, a mask, and glasses, consider protective coveralls
• Wet down cocoons before removing them
• Scrape cocoons and drop them in soapy water; let them soak overnight then dispose of them
Even if one does not plan to remove cocoons, one should become familiar with their appearance, and learn to avoid them or wear appropriate protective clothing during outdoor activities that might bring one in contact with them.
Browntail moth caterpillars wander and form their cocoons anywhere. Favorite places include under the eaves of buildings or the undersides of anything (reports include vehicles, and even a baby stroller), and wrapped in the leaves of any plant.
Traveling within the cocoons on vehicles, outdoor equipment, and other items (including firewood) is a very efficient means of spread for this moth. If one has plans to travel between the affected and unaffected areas over the next month, one should check belongings closely for these cocoons. This winter, be on the lookout for the telltale webs in new places — these are the places where control will be most effective!