CONWAY — Chomp, chomp, chomp. That’s what I imagine I hear as I walk into my yard on a warm summer night. The sound is somewhere between the crackle of a distant campfire and the dripping of gentle rain on spring leaves.
It is neither of those things. It is the sound of falling frass hitting leaves on its way to the ground, along with bits of the leaves themselves, which are systematically being removed, tree by tree, by the gypsy moth caterpillars that have infested my neighborhood.
“Frass” — that’s a fancy word for insect poop. The tiny, amazingly uniform greenish brown pellets littering the ground wouldn’t be particularly noticeable except for the facet that when it rains, they form a particularly slick and sticky mud.
From Birch Hill on the west side of North Conway to the Ossipee Pine Barrens east of Route 16, locals have reported an explosion of caterpillars this year, along with the corresponding devastation to trees.
Insect and forestry experts, however, say not to despair: The good news is that — although most people find the insects disturbing if not disgusting — the damage isn’t permanent and most trees bounce back from the caterpillars’ assault.
“The important message is for people not to worry about it,” said Kyle Lombard, with the state Division of Forest and Lands.
“If an oak is healthy, it’s going to put out a second set of leaves in July and it’ll be just fine,” said the Concord-based entomologist.
For Kent Nutting of North Conway, the caterpillars have invaded not only his trees but his yard and the exterior of his home. Nutting likes to cook on his grill and enjoy dinner on the patio, but not this year. These days he’s outside only long enough to flip the burgers then quickly takes them inside.
“I feel like a prisoner in my own home,” he said.
Nutting said he’s tried to clean the caterpillars off the side of his house but it’s a constant battle. “By the time I’d go around the house once, they’d be back,” he said, adding, “You have to admire their determination.”
His neighbor Chris Perley has another take. “It’s like the zombie apocalypse of caterpillars,” he said, because you keep killing them, and they keep coming back.
Perley tried spraying the foundation of his North Conway home with Ortho bug spray. He said it worked if he sprayed weekly, but he called it a “Scotch victory,” since the caterpillars were still all over the trees.
In terms of the leafless oaks, “you’d think it was the end of November,” he said. “The trees have been devastated right down to the limbs.”
Conway Selectman Dave Weathers said while there are few caterpillars at his home on Route 153, they are very bad in Redstone.
Conway town forester Tim Nolin said, “In the 25 years I’ve been doing forestry, this is the first time I’ve seen a widespread infestation.”
Starting a couple of weeks ago, he said, “you could hear the poop falling down and now you can’t miss it. It’s something that became very apparent very quickly.”
He called upon his predecessor Don Johnson for help because, he said, “it’s difficult to know what we should do here.
“He said one thing you can be sure of is you’ll second guess every decision you make,” Nolin said.
Jeff Lougee, director of stewardship and ecological management for The Nature Conservancy, which owns a large part of the Green Hills as well as a section of the Ossipee Pine Barrens, said both areas are being devastated.
“In the barrens, there’s nearly complete defoliation of the scrub oak understory,” Lougee said, covering about 100 acres of land. “You can see it when you’re driving off Route 41. It’s certainly eye-opening to see the amount of damage an insect like this can do in a short amount of time.”
In North Conway, he said, hundreds of acres of the Green Hills preserve have been defoliated.
For Lougee, “One of the takeaways is predictions around climate change. We will have extended periods of drought, and we may be seeing more of these gypsy moth outbreaks as a result of this.”
Wendy Scribner, UNH Cooperative Extension’s Conway-based forester, said she’s been taking many calls from Conway residents worried about their trees.
“Birch Hill has had a lot of gypsy moths. Oak is one of their preferred species,” she said.
Oak is found on ridges, so that is where the caterpillars like to be. They also like aspens. And in a pinch, they will munch on evergreens.
“They have to be really hungry to do that,” said Lombard.
The entomologist said North Conway has been identified as the epicenter of an outbreak.
“The most intense area starts just north of North Conway and runs down through the Lakes Region, with scattered pockets down through Concord,” he said, adding that exactly how many acres are affected will become clearer after the state does its annual aerial survey in the first week of July.
The survey has been conducted every year for 70 years. Lombard said it is the backbone of the state’s forest health program.
At least one year in the 1980s, he said, it showed a million acres of gypsy moth defoliation. “There was a time through the 1980s we would routinely see a hundred thousand acres of defoliation across the state before the fungus finally started taking effect.”
That fungus, Entomophaga maimaiga, was introduced from Japan n the early 1900s to combat the spread of the caterpillars in the U.S. Repeated applications were made through much of the century and today, it lives in the soil of New England and comes out in wet weather in the spring.
It is devastating for the caterpillars, which quickly start to droop in the middle, hanging on the side of trees, then shrivel and die.
But that introduced fungus can be a problem, too, Lougee said, as it can also affect luna moths and other native species.
Last year, Scribner said, there were some isolated high populations of gypsy moth caterpillars in the Conway area, but this year they’ve definitely taken off.
“They work in seven- to 10-year cycles,” she said, noting, “The population generally crashes after that as natural controls start to kick in.”
In addition to the fungus, the nuclear polyhedrosis virus, or NPV, also causes significant disease when the caterpillar population gets too large.
While some birds, small mammals and insects do eat the caterpillars, Scribner said, the gypsy moth has no significant natural predators in the United States.
That’s because it is an introduced species, brought to Massachusetts from Europe in the 1860s by an enterprising immigrant, Etienne Leopold Trouvelot, who hoped to find an alternative source of silk worms to compete with imported silk from Asia. The moths escaped into the nearby forest, and the rest, as they, say is history.
“We teach about it all the time as one of the great introductions into this country,” said Jim Gore, a retired entomologist whose Center Conway home looks out on the Green Hills, which this summer are brown.
Gore said gypsy moths likely outcompeted a local species which may now be extinct due to the European invader.
Spreading from Massachusetts over the ensuing decades, gypsy moths now can be found throughout the Northeast, as well as parts of the mid-Atlantic states and the Midwest. They reached New Hampshire in the 1920s.
According to the U.S. Forest Service, the caterpillars can spread at a rate of about 13 miles per year.
Peter Pohl, a retired UNH Cooperative Extension forester, remembers the last big outbreak in the 1980s.
“It was horrible,” he said, both because the caterpillars seemed to be destroying trees and because the phenomenon was not well-known or understood.
Living in Sandwich today, Pohl said the nearby Red Hills are populated with oaks and are a study area the state uses to keep eye on potential gypsy moth outbreaks. However, he hasn’t noticed an outbreak there yet this year.
In the ’80s, the outbreak hit there as well as the Ossipee plains, where the pine barrens are, and other high oak areas.
“The previous major outbreaks were in the ’50s, and people’s memories are short,” he said. “It did hit large areas, and people wondered, ‘What is this plague?’ It didn’t prove to be devastating by any stretch of the imagination.”
Over the years, some states have used aerial spraying to kill the caterpillars, but Pohl said New Hampshire has never relied on such methods.
The outbreak, Pohl said, generally happens over three years, with caterpillars being detected in the first year, noticeable in the second and becoming an explosion, with defoliation, in the third.
“It generally collapses on its own at that point,” he said. “One of the factors that affects it is weather.”
Both the virus and the fungus are most effective in wet weather, and experts say it’s likely one reason we are having an outbreak now is because last year there was a state-wide drought.
“Last year’s population was not well-controlled,” Lombard said.
While the weather has seemed dry in the Mount Washington Valley, it is not as dry as last year, and statewide water levels are at their normal levels, he said. “We’re pretty much on track this year. If we’re off, we’re not that far off.”
Back in the ’80s, Pohl recalled, the advice then was much as it is today. Just wait. This, too, shall pass.
In addition to spraying, people tried remedies like wrapping trees in barriers, such as duct tape, to prevent the caterpillars from climbing into the canopy, but he said, “There really wasn’t an effective practical thing to do, so most people did nothing. We just tried to keep them informed and ease their panic.”
Scribner agreed, saying putting a ring of Vaseline or other barrier around your tree “may make you feel better, but I’m not sure it’s going to have much impact as far as tree health is concerned.”
The exception, Pohl said, is if people want to protect individual shade trees, they might try hiring a licensed applicator, who could spray with an environmentally friendly pesticide, generally Bt — Bacillus thuringiensis, a bacteria that not only kills the caterpillars but also breaks down quickly and does not hurt bees or other welcome insects.
Scribner said if a homeowner identifies one or two trees they want to protect, they can contact an arborist to spray them, though spraying can be expensive.
Also, in order to do so, she said you should plan ahead beginning in the winter, when you can see patches of eggs laid by the gypsy moths on trees.
“It’s a little buff-colored patch on the bole (trunk) of the tree,” she said. “You would do egg mass counts in March and April, and line up your spraying in early May” after the caterpillars hatch but before they grow.
To find out more, go to nhbugs.org.
She added: “Deciduous trees can usually stand a year of defoliation. If you have a number of years in a row where this is going on, that’s when it becomes a real problem. You could start to see some dieback, particularly in unhealthy trees.”
Gypsy moth caterpillars go through only one life cycle in a year, with the caterpillar stage taking about four to six weeks in May and June.
The caterpillars grow until they are about 2½ to 3 inches in length, then pupate in small brown cocoons on the sides of trees (rocks, houses, cars — wherever they happen to be).
They hatch in about two weeks into small, white moths, which mate and lay egg masses on trees in August, and the cycle begins again.
More good news: As far as tourism goes, the infestation should have no effect on foliage season.
“The gypsy moth really does not like maple,” Lombard said. And the oaks “are really only in the bottom of the valleys. We haven’t seen any defoliation in the mountains,” he said. “Oak is not a driver of how beautiful our fall foliage is.”
Meanwhile, Conway residents can look forward to another few weeks of caterpillars crawling around.
“I hear people are scared, they don’t want to go outside, and I think, wow, it’s not that big a deal; it’s not a human health issue,” Lombard said.
“Get outside; it’s just a little poop on the driveway, that’s all.”
Of course he’s right. But that’s easy to say when it’s not your suddenly sunny picnic table that the caterpillars have decided to claim as their own.