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Beetles released to help devour invasive hemlock woolly adelgid

The adelgid was first found in Maine in 2003 and has threatened coastal hemlock forests from Kittery to Mount Desert Island.

BRUNSWICK, Maine — In 2003, a Japanese invader began threatening an entire tree species in Maine: the hemlock woolly adelgid.

First arriving in Maine's southern tip, the tiny invasive insect has been moving up the coast, infesting hemlocks as far as Acadia National Park. 

Colleen Teerling, a state entomologist, has been working with 10 land trusts in the late spring and summer, asking them if they would like to release Sasajiscymnus tsugae beetles on as much public land as possible.

The beetles do two things: eat invasive adelgids and mate. 

When NEWS CENTER Maine met Teerling at the Woodward Point Preserve in Brunswick, it wasn't mating time for the beetles just yet.

Some Hemlocks in Maine, dating back to before the Revolutionary War, have become infected. Teerling compared hemlock woolly adelgid to the aphids found on backyard flowers. When a horde, potentially millions strong, gets ahold of a hemlock, they suck out the needles' juices until the tree dies.

Maggie Cozens, a coordinator with Maine Coast Heritage Trust, joined Teerling on a humid June morning to help release the beetles.

"It's been a tried and true method of managing this invasive population," Cozens said.

Teerling explained hemlocks don't just look rugged; they can stand up to climate change better than most other Maine tree species. But, she said, the adelgid thrive in warmth. And if coming winters aren't as cold, adelgids could continue to march north unimpeded.

"If the weather is cold enough in the winter, they just won't establish into, say, northern areas," Teerling said. "But, as the climate changes, yeah, these are spreading faster and faster."

The tedious work goes on. While humans fight climate change, these sides battle it out; with the hemlock woolly adelgid dug in.

Teerling said private landowners will be crucial in this fight. She encourages landowners to contact their local land trust if they're interested in managing Hemlock Woolly Adelgid on their land. 

The beetles can cost $3.50 each if bought in small orders. By ordering in bulk with others, everyone can save money and work to save the trees.

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