Saving hemlocks from tiny invaders, Lefebvre secures $85K state grant

— Photo by Becky Sibner
Hemlocks can live up to 900 years and grow over 100 feet tall.

Marshall Lefebvre speaks of eastern hemlocks with reverence.

“They are a keystone species, foundational for our natural living system,” he said.

Hemlocks, he noted, can live up to 900 years and grow over 100 feet tall.

Yet these huge, enduring trees are being threatened by an insect that is only one-and-a-half millimeters long: the hemlock woolly adelgid, known as HWA.

Lefebvre, who works as the stewardship coordinator for the Mohawk Hudson Land Conservancy, has just secured a $84,989 grant to identify and control the aphid-like insect, an invader from Asia.

The grant, announced this week by the governor’s office, is one of 43 totaling nearly $3 million for projects meant “to reduce the negative impacts of invasive species on New York State’s natural resources, economy, and communities.”

HWA arrived in the United States in Virginia in the 1950s and has been in New York state since the 1990s, arriving in the Adirondacks in 2017, Lefebvre said.

In a video he made about the hemlock woolly adelgid, Lefebvre displays a map that, over the years, shows the spread of HWA from south to north, “expanding like gangbusters as winters start to warm,” he says.

“HWA has already been detected at several of the MHLC preserves including Keleher, Hollyhock Hollow Sanctuary, and Wolf Creek Falls,” Lefebvre states in a 2022 post on the conservancy’s website. 

State Parks is managing HWA at John Boyd Thacher State Park, said Lefebvre.

“They’re hard to find unless you know what you’re looking for,” Lefebvre told The Enterprise. In the summer months, HWA appear as tiny black sesame-seed-shaped spots, but are most noticeable in the winter months with the appearance of tiny white cotton balls on the underside of branches.

Lefebvre will use the grant money to first identify where there are hemlocks on conservancy properties.  He’ll begin with aerial views but says this won’t differentiate between hemlocks and pines.

Staff and volunteers on the ground will then look to see if the identified hemlocks have been infested with HWA. The conservancy already has a stable of volunteers he will call upon but Lefebvre said he wouldn’t turn away anyone who wants to help.

Short-term strategies for controlling or eradicating HWA will involve chemical treatment or cutting trees, he said.

A long-term strategy will be biological control in which natural insect predators of HWA are introduced. This is being done in Albany County at the Alcove Reservoir in Coeymans and at the Huyck Preserve in Rensselaerville.

“It can take time to become effective,” said Lefebvre of biological control.

Time is of the essence because, as Lefebvre said in his video, “They reproduce like crazy.” Each individual can lay 50 to 100 eggs.

Since HWA can reproduce asexually, he said, “They don’t have to waste any time with dating or meeting mates.”

Lefebvre, who became the stewardship director at Mohawk Hudson two years ago, spent five years before that working as a research technician with the New York State Hemlock Initiative at Cornell.

He grew up in southeast Pennsylvania, describing himself as “a dirty, barefoot country boy.” He camped with his parents in the Adirondacks. “That’s how I fell in love with New York,” he said.

His college degree is in conservation ecology, which he describes as a “holistic education of conservation practices with a scientific focus.”

His current focus, and it is fierce, is on saving hemlocks.

“With no checks,” Lefebvre said, “we could see a loss of all hemlocks.”

He goes on to describe how essential hemlocks are to various ecosystems. Some examples: Hemlocks provide the shade over streams that make it possible for trout to live there; hemlocks are vital to 88 species of spiders; many bird species, such as the black-throated green warbler, rely on hemlocks to nest in.

Wild turkey and deer rely on the “microclimate” provided by hemlocks, said Lefebvre, explaining that temperatures around a hemlock are 5 degrees cooler in summer and 5 degrees warmer in winter than surrounding temperatures.

“The list goes on and on,” he said.

Although Lefebvre said, without core sampling, he wouldn’t know the age of hemlocks on conservancy lands, he concluded, “I wouldn’t be surprised if we had some very old trees in protected places like the Bozenkill ravine.”

He also said, “They are 100-percent susceptible.”


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