What is the spongy moth, and what is it doing to our forests?

Spongy moth caterpillars have destroyed trees throughout the Tri-state region.
Peter Steiner
Spongy moth caterpillars have destroyed trees throughout the Tri-state region.
MILLBROOK — One of the major factors in the cycle of the spongy moth and their proliferation — or lack of proliferation — turns out to be acorns.
Spongy moths, formerly referred to as Gypsy moths for their itinerant ways, were the topic of a lecture Thursday, Jan. 11, by scientists Clive Jones, who has studied the spongy moth for 30 years, and Charles Canham, who has studied northeastern forests for 40 years. Both are emeritus scientists of Cary Institute of Ecosystems Studies, which hosted the lecture.
Spongy moths, natives of Europe and Asia, came to North America in 1868 or 1869, to Medford, Massachusetts. Amateur entomologist Etienne Trouvelot believed he could crossbreed them with silkworms in an attempt to “make a hardy silkworm.”
“He got some egg masses of the spongy moth and set them on the sill of his open window. When they blew into his garden, he could not find them,” said Jones.
By 1891, there was mass defoliation in the Medford area and spongy moths were found in a 200-square-mile area. From there, they began to spread throughout the U.S. and Canada.
Alone, the spongy moth travels by ballooning on silk threads; assisted, humans unwittingly transport eggs laid on cut logs or vehicles.
The life of the spongy moth could be said to begin in July and August, when the flightless female moths emit pheromones to tell males that they’re ready to mate.
They each lay a few hundred eggs, often at the bases of trees. If the moth population is high, they lay eggs anywhere, on garden furniture or on the bumper of a car.
Then, the following May, the eggs hatch. The larvae spend May and June ballooning to new locations on silken threads. They rest under trees during the day, then go up into the tree canopy at night to feed. They prefer oaks but also eat maple, beech, apple, hickory, willow and birch trees, among others.
When the population is very dense and the competition for food is fiercer, they may eat all day and night. Once a tree is defoliated, they’ll move to the next canopy.
In late June and July, the larvae pupate — a caterpillar-to-moth metamorphosis that lasts a couple of weeks — then they emerge and breed and the cycle begins again.
Jones explained that “outbreaks” — or high densities of spongy moths — “occur about every 10 years on average, but like any average, it does not mean there will be outbreaks like clockwork.”
There are two major causes of outbreaks, he continued. One is “high female fecundity,” for example: If one moth laid 500 eggs and 250 were female, 125 of those would live to maturity and lay eggs. So, in year two, there would be 125 females laying eggs, and the third year, over 15,000 would result.
The other cause of outbreaks is the collapse of the white-footed mouse population, he said. White-footed mice eat the pupae as a part of their omnivorous diet.
At this point, we reach the subject of acorns:
“The number of mice is determined by the number of acorns the previous fall,” Jones continued, saying that if there is a moderate to large acorn crop in the fall, more mice survive the winter and begin breeding earlier in the year, in late winter or early spring. When that happens, there is an extra generation of mice, meaning more mice to eat more moth pupae.
Studies at the Cary Institute concluded that “moderate to high mouse densities keep moth populations low,” while it was found “that when the mouse population declines, the spongy moth population increases.”
However, defoliation of oaks can cause the trees to produce fewer acorns, meaning less food for the mice, meaning fewer mice the following spring, meaning more moths, and so on, until the moth population collapses again.
There are three major causes of population collapse among the moths.
One is a fungus, Entomophaga maimaiga, which kills the moth at moderate and high densities. It likes cool, wet springs and is more abundant in those conditions.
The more common cause of collapse is Nuclear Polyhedrosis Virus (NPV): When the moths are at high density, they are more stressed by the struggle to find food. Their immunity drops, they are more likely to catch the virus, and many are killed.
The third cause of moth population collapse is lack of food: When they defoliate a large area of trees and run out of food too early, they can’t mature and proceed to egg laying.
Jones said that Cary Institute scientists predict an NPV collapse in 2024: “Whether or not there’ll be a lot or a little defoliation [this year] will really depend on how fast the virus moves through the population. If it moves slowly, there’ll be complete defoliation. If it goes through fast, there’ll be incomplete defoliation.”
Canham continued the lecture by saying, “Defoliation by caterpillars is rarely a direct and immediate cause of tree mortality.”
Canham explained that this is due to “carbohydrate economy”: “Basically, photosynthesis during the growing season produces the sugars needed to produce new tissues, and the energy those tissues need for their metabolism.
“But the even more important outcome of a good growing season is the profit leftover after meeting those immediate needs, and that profit is in the form of sugars and starches that act as reserves for use next year.”
Usually, unless the tree is weakened by other factors, it will draw on its reserves to get through this defoliation and produce more leaves that same year.
An exception that Canham has observed at Cary Institute is the understory hemlocks, which don’t make as many reserves and, after a couple years of defoliation in a row, may not recover. Needle trees, DEEP has noted, can be killed if they lose more than 50% of their foliate.
Canham said he worries more about the devastating effects of the emerald ash borer, longhorn beetle, spotted lantern fly and hemlock wooly adelgid than about the spongy moth.
He said if a tree is in crisis, a way to help it is to water it to “help replenish its reserves.”
For more information or to view the lecture video, go to www.caryinstitute.org/news-insights/lecture-video/...
PINE PLAINS — The Pine Plains FFA Ag Fair brought a crowd to the high school on Church Street Saturday, Oct. 11.
Kicking off the day was the annual tractor pull, attracting a dedicated crowd that sat in bleachers and folding chairs for hours watching Allison-Chalmers, International Harvesters and John Deeres compete to pull the heaviest weights.
A large collection of food was on offer from the Pine Plains FFA and each one of the classes in the Pine Plains Central School District. The football team was selling pickles.
Stissing Mountain High School Principal Christopher Boyd enjoyed a dip in the dunk tank to raise money for the Pine Plains teachers’ union-sponsored scholarship.
Stissing Mountain High School Principal Christopher Boyd got dunked several times during his half-hour shift in the dunk tank. Proceeds from the throws benefitted the Photo by Nathan Miller
The Rev. AJ Stack, center right, blessing a chicken at the pet blessing event at St. Thomas Episcopal Church in Amenia on Saturday, Oct. 4.
AMENIA — After serving more than five years as Priest-in-Charge of St. Thomas Episcopal Church in Amenia, the Rev. AJ Stack announced Tuesday, Oct. 7, that he will resign from the church and Food of Life/Comida de Vida pantry. His last day at his current post will be Sunday, Nov. 2, the conclusion of the Feast of All Saints.
The news was shared in two emails from Stack — one to Food of Life pantry subscribers and volunteers, and another to parish members.
“I write tonight with difficult news, and I wanted you to hear it from me as soon as the Vestry and I had a chance to meet,” he wrote. “After much prayer and careful discernment, I have submitted my resignation to the Vestry as Priest-in-Charge of St. Thomas, and therefore as Executive Director of Food of Life/Comida de Vida.”
Stack provided few details about his departure. At time of publication, he had not announced his next steps but said the decision was “not sudden,” and followed careful consideration over a period of months. He will not be leaving the area or the diocese.
An announcement about his path forward and the transition process is expected soon. In the meantime, Stack said he remains “fully present” at the church, and the food pantry services will continue without interruption.
Stack expressed gratitude for the community and the growth of St. Thomas’ mission during his tenure. “Together we have welcomed new neighbors and strengthened our outreach in meaningful ways,” he said. “I trust that good work will continue.”
He joined St. Thomas in March 2020 and guided the church and community through the challenges of the COVID-19 pandemic. In a recent interview with The News about the food pantry, Stack estimated that it serves 653 individuals from 156 households each week, highlighting a significant contribution to the community.
The announcement was met with messages of reassurance from pantry volunteers. Jolly Stewart, a Vestry member and volunteer, wrote to the community with words of reassurance following the announcement. “I have complete faith in the strength of the parish of St. Thomas,” she wrote. “Our history shows how we have done this time and again, each time becoming more than what we were before. We can, without a doubt, do this now.”
MILLERTON — Ten candidates for office in the Nov. 4 election will answer questions from Dutchess County voters at a candidate forum on Friday, Oct. 24, at the Annex at the NorthEast-Millerton Library located at 28 Century Blvd.
The forum, which is sponsored by the library, will be held from 6 to 7:30 p.m.
Candidates for local and county offices will answer questions from residents in attendance or from residents who have submitted questions in advance.
“We’re excited to keep the tradition of the candidate forum going,” said Rhiannon Leo-Jameson, director of the library. “Some years we can’t always get candidates together.”
This year’s forum will include:
Rachele Grieco Cole, a democrat, and Chris Mayville, a republican, who both are running uncontested for the North East Town Council;
Casey McCabe, a democrat, also running uncontested for North East Justice.
Among Dutchess County races:
Tracy MacKenzie, who is endorsed by Republicans and Democrats,is running uncontested for Dutchess County Family Court Judge;
Kara Gerry, a democrat, and Ned McLoughlin, a republican, are in a contest for a Dutchess County Court judgeship currently held by McLoughlin.
Chris Drago, D-19, and Tonya Pulver, a republican, are competing to represent Dutchess County’s19th District seat currently held by Drago.
Democratic incumbent Dan Aymar-Blair and Will Truitt, the republican chair of the county legislature, are competing for the Dutchess County Comptroller position currently held by Aymar-Blair.
Leo-Jameson is encouraging questions for the candidates to be submitted in advance, which will not be revealed to candidates beforehand. Dutchess County residents may pose questions during the forum. To submit a question on the library’s website, go to the calendar at nemillertonlibrary.org and find the link in the Oct. 24calendar entries.
The format calls for opening statements from the candidates, followed by questions from residents, and candidates will be able to stay after the forum to answer questions personally.
The “Elusive Ki Shusui” koi were temporarily relocated into a tub before being returned to their home pond at Maxine Pietro’s annual koi harvest at Broccoli Hall Farm in Amenia on Friday, Oct. 10. Speaking of their yellowish beauty, Pietro is pictured pointing out that the fish are scaleless but for scales that grow along the “zipper” on each fish’s dorsal ridge. The koi in the photo are estimated to be 6 or 7 years old.