© 2024 Connecticut Public

FCC Public Inspection Files:
WEDH · WEDN · WEDW · WEDY · WNPR
WPKT · WRLI-FM · WEDW-FM · Public Files Contact
ATSC 3.0 FAQ
Play Live Radio
Next Up:
0:00
0:00
0:00 0:00
Available On Air Stations

Milder winters mean more of this insect invading CT’s hemlock trees

A group of scientists from around New England walked through Purgatory Chasm in Sutton, MA to examine the thousands of hemlock trees dying of an insect infestation. The culprit is the woolly adelgid, an invasive species that is decimating hemlock stands and advancing 20 miles a year in New England. The bugs create white wooly sacks on the underside of the lower hemlock branches. The insects die if it gets to be -20 degrees below zero, a situation that is changing in New England because of climate change. Scientists are racing to save the park's hundreds of 300-year-old, 90-foot hemlocks because they frame the quarter mile chasm that is 100 feet deep. There is also great fear it will spread and kill off these majestic trees that are valuable for lumber, dozens of animal species and erosion control.
Dina Rudick
/
Boston Globe / via Getty Images
A group of scientists from around New England walked through Purgatory Chasm in Sutton, MA to examine the thousands of hemlock trees of dying of an insect infestation. The culprit is the woolly adelgid, an invasive species that is decimating hemlock stands and advancing 20 miles a year in New England. The bugs create white wooly sacks on the underside of the lower hemlock branches. The insects die if it gets to be -20 degrees below zero, a situation that is changing in New England because of climate change. Scientists are racing to save the park's hundreds of 300-year-old, 90-foot hemlocks because they frame the quarter mile chasm that is 100 feet deep. There is also great fear it will spread and kill off these majestic trees that are valuable for lumber, dozens of animal species and erosion control.

Cold winters are key to curbing an invasive pest that’s depleted Eastern hemlock trees for decades in Connecticut. Warm winters, fueled in part by climate change, allow these insects to spread — but a deep cold snap in 2023 slowed their advance.

On Feb. 3, an arctic cold front hit the region, wiping out an average of 90% of Connecticut’s hemlock woolly adelgid population.

Carole Cheah, a research scientist with the Connecticut Agricultural Experiment Station, personally visited over 35 sampling sites around the state after the cold snap and saw the impact. The cold snap was so impactful on the hemlock woolly adelgid in part because of a lack of snow to insulate the population.

“Most insects are overwintering; hiding in crevices. They're not out there, exposed to this extreme cold, whereas the adelgid is,” Cheah said.

Winter kill temperatures for adelgid vary based on the area of the state, Cheah said. This winter, temperatures are projected to be “leaning above'' normal in the region, federal weather officials said, but powerful and cold nor’easters are still possible. 2023 brought record-high global temperatures, driven by climate change and El Niño.

Eastern hemlocks have many uses, from sheltering wildlife, improving stream water quality, and creating lumber, paper and mulch. The insect, native to Japan, attaches itself to the stem of the hemlock trees and feeds on its sap.

“It drains the tree’s resources, and the tree is unable to put out new growth. And unfortunately, the health of the trees depend on having this new foliage to photosynthesize and replenish all their reserves,” Cheah said.

Drought also puts pressure on the hemlocks. Historic drought conditions have affected New England as recently as 2020 and 2022, while 2023 brought record rainfall to the region.

Cheah has studied the hemlock woolly adelgid for 30 years and has observed its expansion to new locations in Connecticut, like higher elevation areas. Her team currently uses ladybeetles, a native predator of the adelgid, as a way to control infestations.

The adelgids wiped out in February 2023 were one of two generations that develop every year. Cheah said that for now, this is good news for the state’s Eastern hemlock trees: She’s had to search closely to find more pockets of the pest.

According to new U.S. Forest Service insect research, the adelgid caused damage across almost 6,000 acres of Eastern hemlock trees in 2022.

As Connecticut Public's state government reporter, Michayla Savitt focuses on how policy decisions directly impact the state’s communities and livelihoods. Michayla has been with Connecticut Public since February 2022, and before that she was a producer and host for audio news outlets around New York state. When not on deadline, Michayla is probably outside with her rescue dog, Elphie. Thoughts? Jokes? Tips? Email msavitt@ctpublic.org.

Stand up for civility

This news story is funded in large part by Connecticut Public’s Members — listeners, viewers, and readers like you who value fact-based journalism and trustworthy information.

We hope their support inspires you to donate so that we can continue telling stories that inform, educate, and inspire you and your neighbors. As a community-supported public media service, Connecticut Public has relied on donor support for more than 50 years.

Your donation today will allow us to continue this work on your behalf. Give today at any amount and join the 50,000 members who are building a better—and more civil—Connecticut to live, work, and play.

Related Content