Brown Tail Moth Update

November 3, 2016
Aerial surveys conducted by the Maine Forest Service staff indicate that the infestation by the Browntail Moth in our town and in the region is spreading and we are told to anticipate a much bigger problem next spring and summer.  According to Charlene Donahue, entomologist with the Forest Service, winter nests are visible on many more trees in Bowdoinham and throughout the state. She reported that Bowdoinham seems to be extremely hard hit.  The infestation represents a 6 fold increase since last year at the same time
    At this point in the year, the baby caterpillars are in their winter nests, colonies of hundreds of tiny caterpillar (pupae) wrapped tightly within individual leaves at the tips of tree branches. People can more easily see the small nests when the other leaves fall off  the trees. While the winter nests in the tops of oaks are usually too high to reach, people may be able to clip nests in fruit trees or smaller shrubs.
    Citizens should learn to identify the nests! The webs are often confused with silken structures formed by other less serious species of moths.  Browntail moth winter webs are: 
• 2-5 inches long
• white silk, tightly woven around a leaf or leaves
• wrap of white silk tying leaf petiole to twig
• small, brown hairy larvae within dense silk
• occur more commonly on twig ends of oak, apple, shadbush, cherry, beach plum, and rugosa rose
 
    Clipping and destroying overwintering webs by either soaking in soapy water or burning in a barrel or a woodstove can provide control of isolated populations located in low trees and shrubs. The woven winter nests and the tiny larvae within them DO NOT hold the toxins and generally do not cause a skin rash unlike the hairs of the browntail moth caterpillars that hatch out in the spring.  During the spring and summer, the hairs of the caterpillars can cause both skin irritation and respiratory problems when the hairs become airborne from mowing, raking or other tree work. Still, people should still be careful and limit exposure to skin. 
    Cold winter temperatures do not kill the nests, however wet and cold conditions in the spring may encourage the fungal infection which has been known to kill the young caterpillars. Scientists know very little about the yearly fluctuations of this population and research is ongoing.
    The town staff will continue to gather information about the infestation and to coordinate the sharing of information and resources that become available.  A volunteer task force is currently organizing a panel discussion to educate residents about chemical options to control the Browntail moth caterpillars.  Interested residents can follow “Midcoast Maine Browntail Moth Support” on Facebook, and on the Forest Service website.
    This link leads to fact sheets, history of Browntail infestations, information about the Browntail’s life cycle, instructions on safe handling, and how to identify winter nests - www.maine.gov/dacf/mfs/forest_health/invasive_threats/browntail_moth_info.htm.