For the past few decades the Maine Forest Service has surveyed for browntail moth in coastal Maine. Beginning in 2015 we started to see a dramatic increase in browntail moth populations. This letter is to give notice to towns that have significant detected populations of browntail moth in order to facilitate response by towns and/ or their residents.
Browntail moth caterpillars have hairs that cause a rash and can also cause respiratory distress in sensitive individuals. The hairs may persist for years and can continue to cause problems when mowing or other activities stir them up. The caterpillars eat the leaves of oak, apple, birch and other hardwood and fruit trees from late April to early July. Feeding by the caterpillars may lead to branch dieback and can contribute to tree death after consecutive years of defoliation.
Browntail moth adults fly in July and lay their eggs on host trees. The eggs hatch in August and tiny caterpillars feed by skeletonizing the outer layer of leaves before they make overwintering webs. In summer 2019, particularly in Waldo County, there was enough damage from the young caterpillars that it could be mapped from the air. This and other surveys indicate that populations are potentially very high in parts of some coastal towns and abundant enough to cause significant discomfort in a far broader area.
There were localized population reductions, brought on by a fungus that attacks browntail moth caterpillars which was helped by cool, wet conditions experienced last spring. Unfortunately, these areas still have populations that are above levels that could cause negative human impacts.
The overwintering web survey is ongoing and results will be available in early spring. The survey is conducted from the roadside in areas delineated by the aerial survey or that have experienced problems in the past and expands outward to define the generally affected area. This is not an exhaustive survey. People need to check their own properties to determine their level of risk of exposure to browntail moth.
Below is a link to the Maine Forest Service Browntail Moth website with more information including:
- A frequently asked questions webpage
- Description and images of the browntail moth life stages and how to manage it
- A list of Licensed Pesticide Applicators for landowners to contact this winter about potential control work
- State law specific to browntail moth control near marine waters.
Photo Credit: PHILIP GODDARD / FLICKR/CREATIVE COMMONS