The Maine Department of Agriculture, Conservation and Forestry (DACF) is warning Maine residents that the infestation of a noxious invasive caterpillar is worse this year than last year and local residents should begin thinking now about how they want to deal with the pest. Browntail moth caterpillar hairs can cause a blistery, oozy rash or respiratory distress for people who come into contact with them.

Winter web surveys conducted by the DACF’s Maine Forest Service (MFS) identified extremely high levels over-wintering web in the tops of oak trees for the browntail moth caterpillar. Winter web counts were highest in parts of:

• Bowdoinham, Bath, Topsham, West Bath (Sagadahoc County) Brunswick, Freeport and Harpswell (Cumberland County) this year. Browntail moth webs are also showing up in more southerly places including Cape Elizabeth, Scarborough, Westbrook, Windham, New Gloucester and Yarmouth (Cumberland County).
• Pockets of infestation were also found in other coastal locations from Lincoln County, south and in inland towns such as Augusta, China, Vassalboro, Waterville (Kennebec County), Lewiston, Turner (Androscoggin County), and Whitefield (Lincoln County). One was recently found at Gardiner High School.    

Browntail moth

The browntail moth is an invasive species that arrived in the U.S. around 1910 on nursery stock coming from Europe. It spread through Massachusetts, Maine, New Hampshire and Nova Scotia before the population collapsed. The only place where it is now found in North America is the coast of Maine and Cape Cod.

Browntail moth caterpillar hairs break off the caterpillars and circulate in the air. The caterpillar also molts, and the dried skin containing the hairs can drift, also causing problems for people. The hairs remain toxic for a year or more, so people still can be affected in subsequent seasons.

People should take some extra precautions in areas with browntail moth infestations, especially during the late spring and summer months.  These are especially important during periods of dry weather and include modifying activities that might bring you in contact with the toxic hairs of the caterpillar. 

A list of recommended precautions is available on the department’s website: www.maine.gov/dacf/mfs/forest_health/insects/browntail_moth_precautions.htm.  

For information about the browntail moth caterpillar: http://maine.gov/dacf/mfs/forest_health/invasive_threats/index.htm#btm

For more information about pesticides: www.maine.gov/dacf/php/pesticides/index.shtml

For the list of licensed pesticide companies dealing with browntail moth caterpillar, call entomology lab at: 207-287-2431 or email: charlene.donahue@maine.gov.