LAKE GEORGE, N.Y. (NEWS10) – Over the last two months, anyone surrounded by a lot of trees in the North Country may have heard a telltale chorus similar to falling rain – even while the sky is clear and blue. Now – at least in some parts of the North Country – the telltale tune of the spongy moth caterpillar has gone silent.
On Tuesday, Warren County Soil & Water District Manager Jim Lieberum said that he had seen a downtick in the invasive moth, which last year laid trees bare through much of the Lake George area. This year, he’s seen them show up again, with the month of may less full of rain than is ideal to keep the insect’s population under control. Lieberum, who lives in Thurman, first noticed a change in his own yard.
“I noticed that the caterpillars were just on the trees. They weren’t moving, they were kind of clustering,” he said. “I kept an eye on them, and I assumed that they were ill. They fell down afterward, and like in some parts of the county, they got wiped out.”
The spongy month – whose name was changed from the “gypsy moth” after last year’s boom – lays eggs at the base of trees, near the soil. In a spring season with sufficient rainfall, water entering the soil stirs up pathogens that cull larvae populations before they ever have the chance to hatch, keeping the insects’ total numbers low. In 2021, not enough rain fell to kill off the usual portion of caterpillars that never make it to moth-hood.
Since mid-May, 2022 has begun to look more hopeful. The clustered caterpillars Lieberum found were covered in a white substance – a sign of a virus making its way through the population. As caterpillars, spongy moths make their way up trees and feed on leaves and pine needles, in amounts that can prove lethal for the trees if left unchecked. Caterpillars halted, clustered together and unmoving, comes as a sign that recent rain has given those pathogens the boost they needed, stopping those caterpillars from pupating, becoming moths, and continuing the spread of eggs.
Not all parts of Warren County are spongy-free, though. Fully-pupated moths have been spotted flying around at Crandall Park in Glens Falls, another area that saw lots of moths chewing up the leaves in 2021. The places that did see die-off saw it just in time, with county staff finding plenty of caterpillars thriving and growing in size in places where the rain didn’t make its impact fast enough. Even in places where the caterpillars are surviving in time to pupate, more rainfall could still turn the tide.
“Last year, some (caterpillars) on my property were starting to pupate,” Lieberum recalled. “I cut a tree down – a small pine that had died – and the top was broken out. There were probably 20 or 30 cocoons in there, and I crushed one – disgusting-smelling – and so the virus must have killed them while they were in there.”
Even if the spongy moth has been stopped in its tracks for now, the impact on the Adirondacks is visible. Areas of trees left bare and leafless can be seen around Lake George, Queensbury, and south through to Saratoga Springs.
The leafy trees will re-leaf – they can withstand a few years as spongy moth buffet before their lifespans are threatened. It’s another case entirely for pine trees, which caterpillars can chew through much more quickly, and which can’t grow their needles back as easily. That means that even if the spongy moth boom only lasted through May and June, pine trees on private property and in parts of the Adirondacks may be reaching a premature end of life. How much of a danger death poses can be hard to predict.
“Trees can stay up forever, or fall down at a moment’s notice,” Lieberum said. “You can’t tell what’s going on in the tree, in the ground, and in the root system.”
Any property owner with a dead pine tree in danger of falling onto a house should call a professional to handle it. If the tree is in a backyard or into acres of wooded property, the downed tree isn’t an immediate danger, so much as a change for the local ecology to process. Some years later, there may be more green on the ground around where the tree fell, and more other types of trees coming up in their place.
Lieberum says that some number of spongy moths show up in any given year – if the soil-bound pathogens could wipe them out entirely, there wouldn’t be a problem. Populations can boom, but can only travel as far as adult female moths, which are unable to fly, and therefore lock the population growth down to a certain pace. Even so, there are times when the moths can expand their territory without clear rhyme or reason.
“If you come up in Warrensburg, probably other places, it’s like ‘This oak tree was hit, but this one wasn’t.’ Other places, they’ll be really focused on the oak trees, so the maple trees are okay.”
Those still keeping an eye out for spongy moth caterpillars should know what steps they can take. Now that egg clusters have hatched, double-sided tape similar to fly paper is a popular method. Wrapping it around tree trunks can halt caterpillars from ever making it up into the branches. When all else fails, experts say there’s nothing wrong with going out and picking the invasives off branches by hand.