More Than 100 Years Ago, A Harvard Experiment Helped Spread the Browntail Moth Across New England.

Carrie Jones

Mar 05, 2026

MOUNT DESERT ISLAND REGION—The invasion began with a Harvard professor, a man who was once deemed impractical by the New York Times.

The professor had brought a creature to the United States for study. It was on roses from Holland. The creature had eggs: a cluster of eggs.

And the professor? He had his window open on a windy day.

That wind gusted enough, or blew just right, to lift that cluster of eggs out the window and onto the grounds of Harvard University in Cambridge, Massachusetts.

That sequence began a fight against an invader that’s lasted well over a century in New England.

And that fight? It isn’t over yet.

The browntail moth (Euproctis chrysorrhoea) is still on Maine’s coast and Cape Cod, and still destroying plants and giving rashes. The moths can also cause respiratory distress in humans.

It is also on Mount Desert Island.

Back in 2023, Bar Harbor Code Enforcement Officer Mike Gurtler, acting as the town’s safety officer, tried to inform townspeople to get battle ready against the browntail moths, which decimated the 100-year old elm trees at Harvard back in 1912 and haven’t really stopped though the cycles of devastation have waned and resurged.

“Its fecundity is amazing. The poisonous nature of its contact with human individuals is undoubted,” an unnamed reporter for the New York Times wrote in its July 1, 1909 issue.

The reporter wrote, “We trust the agricultural departments of both states (Massachusetts and Connecticut) will be lavish in spending money” to stamp out the moths.

They weren’t. Or if they were? It didn’t work.

The caterpillars have continued to ravish oaks, willows, elms, and apple trees. They even eat shrubbery and vines.

“Browntail moth concerns have multiplied over the past few years in Bar Harbor,” Gurtler said in 2023. “As the town’s health officer, I encourage residents to help themselves and their neighbors by addressing possible infestations in the spring when the insect’s tents can be removed to prevent the growth of the caterpillars.”

According to a 2019 statement by Acadia National Park, the moth “was reported by a visitor on Great Head and confirmed by a Maine State entomologist in March 2019. Browntail moths have been in Maine for over a hundred years and have gone through occasional outbreaks, but have become quite numerous along the mid-coast of Maine in recent years.

February was the state’s month for awareness about the moth.

The Maine Department of Agriculture advises, “Check trees this winter to see whether your community may be impacted by browntail moth this spring. If you find winter webs, take action to make a difference!”

It advises to “look for palm-sized BTM (browntail moth) winter webs at the tips of trees to see if you may be dealing with BTM caterpillars in the spring and summer.”

If you see a winter web, remove it and destroy it in a contained fire or let it rest in a bucket of soapy water for many days before throwing it away.

“Licensed arborists, pesticide applicators, and FAA-certified drone operators may be able to help you remove webs or treat your infested trees to reduce BTM populations,” the state advises.

The caterpillars leave the winter webs in mid-April. That’s when they begin to eat the leaves and buds of their host trees. They feed until late June.

If you come into contact with an infested area during the late spring and summer, you should change your clothes and shower. The state also recommends not have exterior light on in July. Adult browntail moths fly toward the light, head to your dooryard, and lay their eggs in the trees.

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Parts of this story were originally printed in 2023.

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The Bar Harbor Story is generously sponsored by Acadia Brochures of Maine.

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LINKS TO LEARN MORE

To learn more about the moth via the state.

https://timesmachine.nytimes.com/timesmachine/1912/10/06/100378760.html?pageNumber=53

https://www.maine.gov/dhhs/mecdc/infectious-disease/epi/vector-borne/browntail-moth/index.shtml

https://www.nps.gov/articles/browntail-moth-in-acadia.htm

https://timesmachine.nytimes.com/timesmachine/1909/07/01/101888823.html

https://www.maine.gov/dhhs/mecdc/infectious-disease/epi/vector-borne/browntail-moth/index.shtml

All About Browntail Moth Caterpillars (BTM)

Browntail Moth Rash and Infestation: Get the Facts Now

https://www.maine.gov/dacf/mfs/forest_health/invasive_threats/browntail_moth_info.htm

https://www.youtube-nocookie.com/embed/L6VmwsXE3lg?rel=0&autoplay=0&showinfo=0&enablejsapi=0

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