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Keeping the invasive bugs at bay

Ash borers are found in about 30 US states and the woolly adelgid in about 17.

Woolly adelgid. Photo by Nicholas Ionelli

Foresters and researchers track and attack spreading invaders

Shelving Rock Trail offered a shady respite on a warm September day in Fort Ann. Couples here and there strolled beneath the forest canopy toward spectacular views across Lake George and its wooded islands. It was an Indian summer snapshot of an Adirondack scene that might not last. In a decade or so, the trail and its vista could look quite different.

A bug the size of a ground pepper flake is killing these hemlocks—a species accounting for nearly 80% of the trees in the lake’s watershed. The state Department of Environmental Conservation confirmed this summer the second known attack in the Adirondack Park. It was upsetting for a region already dealing with more bad bug news. Just one week before, the DEC announced the first known infestation of emerald ash borer in the Adirondacks.

As surveys for the two invasive species carried on over the summer, the news got worse. Both insects had been in the Adirondacks for longer than officials at first understood, meaning they had spread farther. Researchers have hope when it comes to combatting the hemlock woolly adelgid. They are less optimistic about battling ash borers.

The fates of the park’s ash and hemlock trees now rest on insecticides, predators that eat these invasive species, and public education to identify infestations earlier.

“These are going to be major impacts to the Adirondack Park,” said Gary Lovett, senior scientist at the Cary Institute of Ecosystem Studies.

Getting here

The ash borer and woolly adelgid are invasive species, native to Asia. The woolly adelgid may have first arrived in the 1950s on an imported ornamental tree. But the ash borer was perhaps a sneakier stowaway, likely hiding in wood packaging that made its way to the U.S. in 2002.

Their populations have steadily grown, with the ash borer found in about 30 states and the woolly adelgid in about 17, according to the U.S. Department of Agriculture. Both have reported populations in New York.

emerald ash borer cc chesapeake bay program
Emerald ash borer. Credit: Chesapeake Bay Program

The emerald ash borer was already documented in counties surrounding the Adirondack Park, so many were more disappointed than surprised when some trees on the Schroon River were found infected. A highway department worker noticed the sick ash trees at the Warren County boat launch. Sure enough, they were nearly dead and filled with ash borer larvae.

The hemlock woolly adelgid has made an appearance in the Lake George area before, spotted in 2017 on Prospect Mountain. A quick response to the infestation showed the invasive bug was on a couple of trees.

Little did anyone know that the tiny insect was multiplying about 27 miles up the eastern side of the lakeshore in Washington County.

If scientists could, they would turn back the clock and keep the bugs out of the country.

“Prevention is without a doubt the most cost-effective method of dealing with invasive species,” said Mark Whitmore, a forest entomologist at Cornell University. “It needs more attention.”

Prevention is Lovett’s main platform.


“The hemlock woolly adelgid and the emerald ash borer, they’re two separate problems, but they’re both symptoms of the same problem,” Lovett said. “We keep letting these invasive pests into the country through international trade.”

Lovett and a group of scientists have proposed policy recommendations called “Tree-Smart Trade.” They involve things like switching to alternative packaging material so forest creatures cannot hide in wood packaging, restricting the importation of live plants and increasing surveillance of shipments.

Lovett also thinks governments need to invest more in monitoring programs so they can fight outbreaks while they’re small. A camper at DEC’s Glen Island Campground discovered the woolly adelgid.

Environmental groups in the Adirondacks and elsewhere aren’t doing enough to lobby for stricter regulations, Lovett added. Many will tout their monitoring and surveillance programs.

“People feel better that they’re doing something about the problem, but really what we ought to be focused on is what’s the next pest and how do we keep it out?”

Southern Hemisphere vigilance

Australia and New Zealand, Lovett said, are the paragons of invasive species management.

Whitmore also pointed to New Zealand as a prime example. After Lovett visited New Zealand about a decade ago, he recalled the scene at the airport where customs took away his hiking boots. He waited patiently for five minutes or so, until they were returned in a plastic bag.

“They had been sprayed with something,” Lovett said. “They’re really serious about making sure you don’t import soil, plants or anything into New Zealand.”

In the United States, the Department of Agriculture is the lead agency tasked with keeping invasive species from entering the country, through its Animal and Plant Health Inspection Service (APHIS).

APHIS’s plant protection and quarantine experts are always assessing invasive species risks, said Rhonda Santos, a public information officer. She specifically pointed to something called the International Standard for Phytosanitary Measures 15. One practice it describes is to treat and debark the wood that will be used in packaging.

The program began in 2005, but not all countries participate. Santos said APHIS believes the standard’s effect will grow as more countries join the U.S. as adherents.

Santos works on a team focused on the emerald ash borer. The future of ash is already so dire when it comes to this bug that the federal government is actually proposing to remove any quarantine regulations for it. Given the challenges in controlling ash borer’s spread, Santos said, APHIS wants to redirect resources toward more promising efforts—including rearing and releasing “biological agents.”

To report a possible emerald ash borer infestation to the USDA, call 866-322-4512. To report signs of hemlock woolly adelgid or emerald ash borer to the DEC, go to or call 866-640-0652. Submit locations to, or to

Cue the stingless wasps.

Hope for ash

Biological control is a fancy term for a living creature that is a kind of enemy of another. A few species of stingless wasps have shown to be parasites to emerald ash borer. Some eat the ash borer larvae.

Santos confirmed that the agency is considering the Adirondack Park for its biological control testing in 2021. The wasps were first released in Michigan, and Santos said they appear to be working.

“Our cooperators have difficulty finding late-stage EAB (emerald ash borer) larvae,” Santos said. “That is a strong indicator that the parasitoids are successfully killing EAB.”

APHIS has released more than 8 million such parasites in 30 states and the District of Columbia, and they have established in at least 22 of the states. The USDA is funding research, too, into the genetics of a few ash trees that have survived an ash borer attack.

For Charlie Canham, it’s not enough.

“To be honest, the emerald ash borer is just a horrifyingly depressing story,” Canham said. Lovett’s colleague and a senior scientist at the Cary Institute, Canham sees little hope for biological controls knocking out ash borers in the park.

Schroon River

At the Schroon River boat launch where DEC confirmed an infestation in the park, Tammara Van Ryn stood at the foot of the species she called “as American as baseball.” Ash trees used to be the premier wood for making Rawlings Adirondack baseball bats, but since the trees’ broader decline, other species are filling in the gaps.

Three ashes in the parking area were stripped of their bark around the base, revealing serpentine galleries where ash borer larvae had been munching. In a desperate attempt to survive, the trees shot out baby limbs with bright green leaves.

Van Ryn, manager of the Adirondack Park Invasive Plant Program (APIPP), and Rebecca Bernacki, terrestrial invasive species project coordinator, were there to conduct a 5-mile radius survey to see what other ashes the insects may have colonized. The borer’s telltale sign is a D-shaped exit hole, but it’s difficult to see when the bark is still wrapped around the tree.

Van Ryn and Bernacki also look for the shoots of new leaves, a blond trunk toward the top of the tree and woodpecker holes. Woodpeckers eat the larvae, Bernacki said. The trees on the Schroon River were likely infested with the insect for two or three years, which is about the time it takes the bugs to kill. DEC said the infestation had spread beyond the boat launch to neighboring private property. About 7% of New York’s forest is ash.

Though the percentage is smaller in the Adirondack Park, Van Ryn and others consider the species’ potential loss there heartbreaking. Another problem, Bernacki said, is that invasive plants typically take over where ashes die.

Cultural connections

“When you see beautiful ash, it’s gorgeous,” Van Ryn said. “It’s definitely going to change the landscape.” It could also change a way of life for the Akwesasne, a Mohawk Nation reservation on the St. Lawrence River north of the park. Les Benedict, assistant director for the Akwesasnes’ environmental division, said emerald ash borer has been a “slow-burning fire” for two decades.

“Sometimes, with everything else going on in the world, we tend to forget about things that are happening that are very important,” Benedict said, “and more important than many people can appreciate until it’s too late.”

Ash, especially black ash, is personal for the Akwesasne. They use it to make baskets. The baskets are for everything from catching fish to washing corn. They were the inspiration for the Adirondack pack basket. But they’re also ceremonial. A bride and groom, for example, exchange baskets on their wedding day. They’re meant to contain what each partner brings to the union—food or commitment to provide, for instance, Benedict said.

“Today, it’s an expression, a connection to our past.”

Canham also builds boats and often uses white ash. Van Ryn said ash tends to be a good firewood, though that’s one reason the pest moves so readily. State regulations prohibit transporting untreated firewood more than 50 miles. It’s illegal to transport regulated pests in New York, too.

“If you were to be stopped by DEC and they saw this was emerald ash borer, you could not drive that firewood anywhere,” Van Ryn said. “But what are the chances of finding that and what’s the chance of the landowner ever knowing (about the emerald ash borer)?”

“Most people just don’t know what to look for,” Bernacki added.

White fluff

The woolly adelgid is trickier because it’s not just humans that move it from place to place. The bug is so small and light in its crawler stage that the wind will pick it up and carry it to a new home. Birds and other wildlife could give it a lift, too. In the winter, fluffy white sacs are more easily spotted on the underside of the hemlock branch.

Those are the adelgid’s wool, which it develops for laying and insulating its eggs. State Forester Rob Davies believes the woolly adelgid population afflicting about 250 acres on Lake George arrived via birds. That’s because most of the invasive insect is established on shoreline trees where birds tend to congregate.

It doesn’t bode well for the most prominent tree on the Lake George shoreline. Hemlocks shade waters for trout and stabilize shorelines and uphill areas from stormwater run-off. They’re a major water quality protector.

“The infestation that we are finding is older than we had hoped and larger than we had hoped,” Davies said. “Just how long it has been is a question, but we do feel as though the infestation is more than five years old at this point.”

Ezra Schwartzberg, an entomologist and director of Adirondack Research, said that means the woolly adelgid is surviving Adirondack Park winters.

“We didn’t really know if hemlock woolly adelgid could survive in the Adirondacks, but with this new infestation, we know it can,” Schwartzberg said. “Now our priority is to see if there are undetected populations of HWA in the Lake George watershed.”

Patrolling Shelving Rock

With a team of three others, Schwartzberg hiked around the Shelving Rock Trail area in Fort Ann at the end of September. With funding from the USDA, Adirondack Research is using NASA satellite imagery and on-the-ground surveys to delineate all the hemlocks in the Lake George watershed. The DEC, Lake George Land Conservancy and the Adirondack Park Invasive Plant Program are also partnering with Schwartzberg on hemlock surveys in the area.

Jamie Brown, director of the land conservancy, said so far the bug has not been spotted on any land conservancy property. Whitmore and his team at the New York State Hemlock Initiative are also out surveying, climbing trees and examining their canopies.

Woolly adelgid are not easy to spot, especially this time of year. Schwartzberg uses a hand lens magnifier and reader glasses to see the crawlers. Sometimes he needs a flashlight in the shaded forest.

The Fund for Lake George, the DEC and APIPP also announced a partnership to use satellite technology for monitoring woolly adelgid infestations in the region. The idea is to look for changes in the hemlocks’ shades of green.

Adelgids don’t kill trees immediately, Whitmore said, but start by attacking buds. The trees may still have needles but won’t produce more. “So that’s the insidious thing. It looks green. It looks just fine to the untrained eye, until it’s too late.”

Satellites help spot where hemlocks are declining and how large the population of woolly adelgid might be, Schwartzberg said. The best way to find an early infestation, however, is to check branches in person.

DEC is “absolutely confident that we can control this infestation,” Davies said.

The state and its partners will use insecticides at the base of the infected hemlocks, and the trees will transport it through their circulation. The DEC has said the insecticides are targeted to woolly adelgid and should not harm the tree or other creatures. It will not be a one-time application, but rather an ongoing treatment over several years, Davies said.

Application costs $250 an acre, for a total of $62,500 this fall. Some densely forested acres may need further treatments. Whitmore plans to release biological controls, too. It may have happened prior to this publication.

There are types of beetles and flies that eat the woolly adelgids, and Whitmore has been studying them in his lab for the past decade. The predators come from the Pacific Northwest. Whitmore goes there and collects them, brings them back to his lab and raises them. Then they’re released, with high hopes. It’s a long-term potential solution, Whitmore said. The populations of these predator flies and beetles have to establish themselves and have enough food to eat. That takes time.

They appear to be working in the West. Whitmore hopes biological control can “be a large component of the answer so that we can hopefully save the big, old trees in the Adirondacks.”

Old growth

Some of the oldest trees in the state are hemlocks, according to the DEC—perhaps older than 700 years. That’s around the time when millions died from the bubonic plague in Europe. Now, those trees are living in the time of the coronavirus pandemic. Tiny bugs could end their watch.

Hugh Canham, a member of the New York Forest Owners Association and a retired DEC forester, said he has seen a number of forest pests and diseases come and go.

Gypsy moth was a concern for him during his time at the DEC. Woodlots were destroyed in the Adirondacks. Now, he said, it has settled down. Some pests and diseases have made their mark. Chestnut blight, for example, nearly wiped out chestnut trees.

“Well, life goes on,” he said.

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