These overwintering webs of the browntail moth in a hawthorn could easily represent more than 4,000 caterpillars next spring. Clip and destroy webs within reach now, especially from isolated trees, to help reduce impacts from the browntail moth later.
Feb. 26 to March 2 was National Invasive Species Awareness Week, entomologists from the Maine Department of Agriculture, Conservation and Forestry remind people that now is the time to remove browntail caterpillars from trees that are accessible. Browntail caterpillars cause a poison ivy-like rash and they are impacting a broad swath of Maine. Contact with this caterpillar’s hairs can cause severe reactions for some individuals.
Browntail caterpillars spend the winter webbed in silken-wrapped leaves on the tips of branches of oak and apple trees. Now is the time to look for the bright white silk tying a few leaves to the tips of one’s apple and other fruit trees and oak tree branches. If one sees a web, one should clip it out and destroy the web by dropping it in a bucket of soapy water and soaking it overnight; do not just leave it on the ground. The caterpillars are ready to go once warmer weather arrives, so do this task as soon as possible.
Browntail caterpillar webs can be found regularly in Maine from the New Hampshire border to Deer Isle, and inland to Raymond, Turner, Rome, Smithfield, Burnham, and Eddington. They are worst along the coast from Falmouth to Bristol and up the Kennebec River to Richmond. In 2017, outlying patches of defoliation were found in the towns of Belgrade, Burnham, Eddington, Liberty, Lincolnville, Turner, and Whitefield. The moths have been seen all the way west to Kingfield, north to Ashland, and east to Topsfield on the New Brunswick border.
This web clipped from a crabapple tree could have more than 400 caterpillars in it. As those caterpillars grow, contact with hairs from them cause a rash for most people and can cause serious reactions in sensitive individuals. Clip webs and soak them in a bucket of soapy water overnight or destroy to reduce the numbers of larger caterpillars this spring and summer.
As people have heard, “an ounce of prevention is worth a pound of cure.” People have known that to be true of browntail for more than 100 years. One can learn how to recognize browntail moth webs by visiting the websites below, then going out and checking trees for their presence. If one cannot reach the webs to clip them out, now is the time to line up professional help for this spring.
If one does not have trees, one can survey a public space in one’s town. If one thinks one has found webs but is not sure, one can contact the forest service for help at maine.gov/dacf/mfs/forest_health/tree_ailment.html.
Background information, a video showing how to clip the webs, a list of arborists who could prune webs out of one’s reach, and a list of licensed pesticide applicators that can treat the webs can be found at maine.gov/dacf/mfs/forest_health/invasive_threats/browntail_moth_info.htm.
For more information, contact the Maine Forest Service at 827-1813 or one’s local University of Maine Cooperative Extension office.
