Moth Mayhem: A Generational Tale
- Christy Phillips
- Apr 21
- 4 min read
History of Browntail Moth (BTM) in Maine:
A thriving natural environment depends on biodiversity - and that includes pollinators. Pollinators native to Maine include 270 species of bees, 120 species of butterflies, 292 species of birds, and between 500–800 species of moths.
In any ecosystem, plants and animals exist in a symbiotic relationship. These relationships can range from beneficial, neutral, or harmful. A healthy ecosystem is one where the symbiotic relationships are beneficial or neutral. Many insects rely on specific plant species for survival and reproduction. In a typical symbiotic relationship, an insect lays its eggs on a host plant, and the larvae feed on that plant once they hatch.
In balanced systems, this behavior doesn’t destroy the plant. Native species have evolved within these systems, so their interactions tend to be neutral or even beneficial. However, not all pollinators in Maine are native. Non-native species can disrupt these relationships. They often lack a natural predator and cause significant harm to an ecosystem - this is what makes them invasive.
Meet the Browntail Moth:
One invasive species that has become increasingly noticeable in Maine is the brown-tail moth (BTM). Browntail moths are harmful to both forest and human health. They are tree- and shrub-dwelling insects that prefer species such as oak, apple, cherry, crabapple, elm, birch, poplar, shadbush, and rugosa rose.
Impact on Human Health
The caterpillars have toxic hairs that easily break off and become airborne. These hairs can cause skin irritation and respiratory issues. The resulting rash is similar to one caused by stinging nettle, but it can spread across the entire body - even in areas that did not directly contact the hairs - due to a systemic reaction.
Impact on Ecosystem Health
Unlike native species, brown-tail moths do not maintain a balanced relationship with their host plants. Their caterpillars feed aggressively on leaf buds before the buds can fully develop, often defoliating entire trees and shrubs.
Mid-April marks the emergence of caterpillars from their winter webs. From that point through late June, they feed on the developing leaves of host trees.
Life Cycle
Browntail moths have a unique and particularly persistent life cycle:
August: Eggs are laid
Fall: Eggs hatch, and caterpillars begin feeding and building their nests.
Winter: Caterpillars live in winter webs for up to 8 months
Mid–Late April: Caterpillars emerge and feed on leaf buds
Late April-June: Caterpillars munch on leaves, often defoliating entire trees
Late June: Caterpillars pupate
July: Adult moths emerge and mate
Toxic hairs from BTM caterpillars can be present in the environment from December through July.
Although highly invasive, thankfully, brown-tail moths are not entirely without natural controls. Their populations can be impacted by predators, parasites, fungi and viruses - though these factors have not been sufficient to control populations in Maine.
How Did They Get Here?
Native to Europe, browntail moths were introduced to Massachusetts in 1897. By 1913, they had spread throughout New England.
Their populations declined during the mid-to-late 20th century - likely due to management efforts and natural factors. However, they resurged in the 1990s and have remained a persistent issue ever since. This resurgence has been linked, in part, to Maine’s warming climate.
Yarmouth’s History with Browntail Moths
After speaking with Dr. Katie Worthing of the Yarmouth Historical Society, I had the opportunity to read through some historical documents that highlighted just how long browntail moths have been a concern in the area.
In 1905, The Town of Yarmouth operated on a budget of $21,845 (equivalent to over $700,000 today). Of that, $50 (about $1,500 today) was allocated to brown-tail moth extermination.
By 1907, this allocation increased to $100 within a Town budget of $23,815. Records indicate that most of BTM budget allocation was spent on nest removal, however a smaller portion was used as funds for postage, notices, and even a prize - likely awarded for successful nest destruction.
This same era marked Maine’s first official publication on browntail moths. In 1905, the state allocated $5,000 toward management efforts. That year, approximately:
1,000 nests were destroyed in Yarmouth
175 in Falmouth
122,000 in Portland
Newspaper reports from 1907 describe widespread infestations across southern Maine. One report noted large numbers of nests near waterfront areas and suggested that moths may have been transported via steamships from Boston. Inspectors even proposed placing agents on ships to destroy moths before they could spread inland.
“Like a Moth to a Flame”
In 1910, Yarmouth experimented with a creative control method: a mechanical “moth destroyer” imported from Germany.
This device functioned as a light trap combined with a vacuum. Bright lights attracted the moths, and once they came close, they were sucked into a tube and killed against a wire screen. To increase effectiveness, all other lights in town were turned off.
On its first night of use, the machine reportedly destroyed “several thousand” moths. Plans were even made to install a permanent version atop one of Yarmouth’s mills.
What Can We Do Today?
Although municipal budgets and control methods have changed significantly over the past century, browntail moths remain a persistent problem.
Through Yarmouth Community Services, the Town continues to provide information on BTM and manage the pest on Town-owned properites.
Remove winter webs: Clip and destroy webs during the winter months. Dispose of them in soapy water or by burning (where permitted).
Hire professionals if needed: If webs are out of reach, consider contacting a licensed arborist.
Use insecticides carefully: Treatments are most effective from mid-April to mid-May, when caterpillars are small.
Curious about learning more about safe lawn care practices? Check out this workshop on 05/05 at 5:30
Safety Tips
Learn to identify browntail moth caterpillars
After exposure, shower and change clothes (similar to poison ivy precautions)
Limit outdoor lighting in July to reduce attraction of egg-laying moths
In addition to the resources linked throughout this article, this blog post was informed by materials from the Yarmouth Historical Society, a workshop on ecological gardening taught by Kelly Corbin, and knowledge and feedback from Town staff and Town committee volunteers. Photos are from the State of Maine and The Metropolitan Museum of Art.
