A browntail moth clings to a wall on a Main Street business in Lewiston on July 8. Russ Dillingham/Sun Journal
On a Saturday morning in May of 1897, Joseph Pike of Somerville, Massachusetts, noticed that an insect was gobbling up the leaves on his pear trees.
He quickly notified the office of a committee spearheading the fight against gypsy moths in the Boston area. It sent Fletcher Osgood over to have a look. He advised spraying the trees with arsenic to kill the bugs.
But in the weeks that followed, experts soon discerned that the insect Pike discovered in his yard wasn’t the gypsy moth at all.
Professor Charles Fernald at Amherst College figured out it was, instead, the browntail moth, a well-known scourge in Europe that had never been seen before in the New World.
Authorities knew immediately they faced a major problem — and began taking steps to try to wipe out the moths.
In a 1905 booked titled “Illustrations of the Ravages of the Gypsy and Brown Tail Moths,” one picture showed men burning browntail moths by spreading oil and setting it on fire. Medford Mercury
From the vantage point of 2021, it’s easy to see they failed in that endeavor. The lustrous white moths are turning up in large numbers this year through much of central Maine, having long since spread from the Boston area to a wide swath of America.
Normally, they’re just another invasive species causing problems for native habitat but some years, this one among them, the browntail moths are clearly a far bigger concern than usual, due in part to the rashes and itching their tiny hairs can cause for unwary or unlucky humans, especially when they’re still in their springtime caterpillar stage.
A browntail moth caterpillar climbs across a leaf on a tree in the Androscoggin Riverlands State Park in Turner. Andree Kehn/Sun Journal
This time of year, the moths lay eggs that typically hatch in August, when caterpillars emerge. They eat until it gets too cold, then nest until spring, when they’re voracious until they spin themselves into a cocoon in June to emerge in July — as the moths that are now becoming a common sight in some areas of Maine.
In the Old World, browntail moths were long seen as an enemy. Priests excommunicated them in Spain and the French passed laws barring them, not that the bugs cared as they gobbled up entire forests in England and denuded trees from Belgium to Bulgaria despite desperate, and wholly unsuccessful, efforts to exterminate them.
INVESTIGATING THE NEW MOTH
The Committee on the Gypsy Moth, Insects and Birds — created in Massachusetts to try to control the spread of gypsy moths — sent investigators out to Somerville to try to learn more about the latest invasive species to reach the shores of the Bay State.
What they found must have been discouraging.
A view of Somerville, Mass., in the early 1900s. Somerville Board of Trade
A Vine Street resident, W.I. Chase, told probers that when he moved to his home in 1892, caterpillars had defoliated his pear trees and then descended onto the ground to ruin his rhubarb and take aim at his garden. He’d never been able to get rid of them entirely and, in 1897, they’d stripped the leaves off nearly every tree he had.
His wife said the house and yard “fairly swarmed with white moths” during the previous summer.
J.A. Merrifield, who lived on Somerville Avenue, said he’d seen the insect in his pear trees for at least several years, but had taken care to cut off and destroy the caterpillars’ tent during the winter, preserving his trees while neighbors saw theirs defoliated.
But in 1897, Merrifield got busy in the spring and didn’t get around to the work until Patriot’s Day on April 19. It proved too late, the committee said, and the caterpillars were already “crawling over the twigs in great numbers” within weeks.
Resident after resident told investigators that they’d watched helplessly as the insects devoured everything in sight.
While nobody could ever say for sure, authorities strongly suspected a greenhouse right in the middle of the infested area likely imported the moths along with the roses and shrubs it had shipped in from Europe.
Fernald wrote in a book about the moths that behind the greenhouse were two blocks “of large, full-grown pear trees, and these trees were completely defoliated by the caterpillars, and had a history of repeated defoliations extending backward for three or four years.”
BOSTON TRIES TO FIGHT THE MOTH
Fully aware of the danger they faced, authorities hightailed it to the Legislature in hopes of snagging an appropriation to pay for the cost of suppressing the insect.
A state representative from Lowell asked the state to match the $150,000 allocated for the fight against the gypsy moth.
But his colleagues saw the chance to get money for other causes as well, with one pushing to fund the effort to combat canker worms, a chicken parasite whose presence inhibits egg production, and potato bugs that eat the stems and foliage of potato plants.
By the time lawmakers finished debating the issue in June 1897, the state House overwhelmingly decided to offer no funding but it did order local authorities and property owners to aid actively in ridding the area of the insects.
Removing browntail moth nests from a Massachusetts orchard about 1900. Massachusetts State Board of Agriculture
Despite the short-sighted refusal by politicians to pay for an all-out bid to rid Massachusetts of the moths before they spread far and wide, about 100 employees of the committee tried to fight back, slaughtering 100,000 of the browntail moths daily. A million trees in the Boston area were sprayed with poison, usually containing arsenic or lead.
Even so, by July, the invaders were found in the Saugus woods north of Boston. That fall, experts also found a single afflicted tree in Scituate, south of Boston, a sign that the insects had spread in every direction from Somerville.
In December 1899, C.F. Moulton, an investigator for Massachusetts’ Board of Agriculture, found a moth in Seabrook, New Hampshire.
The board cited the find as an indication of “the rapid spread of this insect, with its well-known capacity for injury” and “well illustrates the folly of allowing these foreign insect pests to become disseminated in this country, where intelligent, persistent effort, with a reasonable outlay of money, would secure their suppression.”
The Boston Globe in 1904 urged readers to “remove all nest and larvae of this pest” by cutting down nests and burning them in stoves and furnaces “or they can be piled up in the backyard.
“Pour a small quantity of kerosene all over them and set them on fire,” the paper advised. “This will be safe enough provided you don’t make the pile too big.”
Browntail moths were found surrounding Boston by 1899, with the heaviest concentration north of the city. Massachusetts State Board of Agriculture
THE MOTHS ARRIVE IN MAINE
The first report of browntail moths in Maine came in 1899 when a University of Maine professor, F.L. Harvey of Orono, found some in Kittery. They got there along with some household goods “from a badly infested Somerville estate at a time when the insect was in the cocoon stage,” Fernald said.
A Boston and Maine train in New Hampshire about the turn of the century. Dover, N.H. Public Library
By the spring of 1902, Fernald said, “the nests of the moth could be seen easily from the car windows in every town along the eastern division of the Boston & Maine Railroad from Boston to Portsmouth.”
Trains, indeed, may have been a big reason for the quick spread of the bugs.
“It is not difficult to understand how the swarming insects driven by the wind from the place of emergence fly onward to the nearest mass of light,” Fernald said. “This tends to bring about the infestation of the central portions of cities and towns before the pest finds its way to the outlying residential or farming districts. “
During flying season, he said, the moths “enter brightly lighted electric and street cars,” where open windows “give the insect easy entrance” and distribute them up and down the rail lines that in those days tied the entire region together.
The first big outbreak noticed in Maine didn’t come until 1905.
That March, for instance, officials in Bucksport found “what is probably the most dangerous insect pest that has ever invaded the state,” as the Bangor Daily News reported.
Many nests were found in the town and authorities worried that many more were likely strewn among the trees and shrubs that hadn’t been examined.
That first report warned people that the caterpillars eat the leaves of fruit, shade and forest trees and that their hairs “produce a serious and painful case of poisoning” if they come in contact with human skin.
“For the sake of all,” the story urged people “to destroy” every nest and keep the browntail moths out of the Pine Tree State.
That spring, though, browntail moths were found all along the coast past Portland and in many other spots, including Lewiston and Auburn. York County was touted as a particular hot spot for the insect whose nests were also found along the Kennebec River in Augusta, Belfast and a good chunk of Cumberland County as well.
By 1906, they were found on Mount Desert Island.
MAKING WAR ON MOTHS
For the next 15 years, authorities throughout New England, including Maine, tried valiantly to exterminate the invading moths.
A 1910 photo shows a burn pile with many browntail moths waiting to be incinerated. U.S. Department of Agriculture
They killed them by the hundreds of thousands with poisons, clipping off their nests and setting them afire and many more schemes.
They cut down fruit trees, sometimes whole orchards.
At the same time, they tried to keep the infestation from spreading further. In 1917, the federal government banned the region from exporting Christmas trees in one bid to fight the moth.
Perhaps most importantly, they released parasites imported from Europe and encouraged more English sparrows to flourish in the belief they’d eat the bugs. At least 15 natural enemies of the moth became established as a result of U.S. Department of Agriculture efforts in the two decades after 1901.
Entomologists infected moth larvae with a naturally occurring fungus starting in 1908 that spread through moth populations in Massachusetts, perhaps reducing the number of moths in the process.
None of it could be shown for sure to do the trick. But something helped.
By the 1920s, the population of browntail moths collapsed. They mostly vanished save for a few spots, including an outer portion Cape Cod and some Maine islands. Experts think that changes in weather played a role and so, too, did the growing number of parasites that afflicted the moths.
Even so, a 1943 outbreak saw the moths infesting treetops along the river in Lewiston, forcing authorities to devote considerable attention to cutting down their winter nests before the caterpillars emerged in the spring, the Lewiston Daily Sun reported. Fruit trees throughout the area appeared to be especially vulnerable to the insects.
THE MOTHS MAKE A COMEBACK
Maine Forest Service map showing results of an aerial and winter web survey during the winter of 2021 of browntail moth concentrations. Maine Forest Service
The moths began making a comeback two decades ago, but with only localized problems.
Since 2015, though, there’s been a growing outbreak of browntail moths in Maine and beyond.
Last year proved a banner year for the bugs, probably because of hot, dry conditions — and this year didn’t see any improvement.
The shifting weather has helped the moths bounce back back in many areas of the Pine Tree State as a consequence.
“Most areas of Maine, especially along the coast and inland that have significant host tree populations, are at risk,” the state Department of Agriculture, Conservation and Forestry posts on its website.
“In 2021, overwintering browntail moth webs were found in every county in Maine,” it says, with the highest populations in Androscoggin, Cumberland, Kennebec, Knox, Lincoln, Sagadahoc and Waldo counties. The southern portions of Oxford and Franklin counties are also at risk, the department said.
Are browntail moths going to be a long-term worry? It’s hard to say.
A 2021 study for Environmental Entomology by researchers for the University of Maine and the state concluded that “it is difficult to predict long-term trends in browntail moth populations.”
“Current climate trends, particularly warming, favors their development, but over time, these same factors may affect the range expansion” of possible competitors as well as plant quality and natural enemies, the study said.
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