May 25, 2018
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Maine Forest Service to release predatory beetles at Vaughan Woods State Park

Photo Courtesy of Department of Conservation
Photo Courtesy of Department of Conservation
Lady beetle

AUGUSTA, Maine — Maine Forest Service entomology staff will release more than one thousand tiny, predator lady beetles Thursday at a Maine state park in an effort to manage a highly invasive insect that is moving up the coast of Maine.

Some 1,500 black lady beetles, known as Sasajiscymnus tsugae, will be released at Vaughan Woods State Park in South Berwick to fight hemlock woolly adelgid (HWA), an invasive insect that kills hemlock trees.

The biological-control effort won’t eradicate the infestation, but it should reduce the HWA population at the park, according to Allison Kanoti, Maine Forest Service forest entomologist, under the Maine Department of Conservation.

“It’s the best management tool we have in the forest at this time,” Kanoti said. “This is a long-term solution; results will not be immediate.”

Hemlock woolly adelgid is a small, aphid-like insect that is covered with white, waxy wool-like material. This wool-like covering makes the insect resemble miniature cotton balls. It is most visible from late-October through July, with woolly masses located on the undersides of the twigs at the bases of the needles. The insect begins its egg-laying in March.

The insect, which came from Japan in the 1950s, causes infested trees to have off-color needles, often with a grayish cast, premature needle drop and twig dieback and eventually mortality.

Hemlock trees are a significant Maine tree species and are one of the major trees found at Vaughan Woods State Park, Kanoti said. Often found near water bodies, hemlocks contribute to the state’s forest ecosystem. Their presence along water bodies helps protect the forest floor from erosion and buffers water temperatures which can affect such species as brook trout. Hemlocks also are important in deer wintering areas, are a favored landscape tree and contribute to the state’s forest products sector.

HWA has been found in at least 16 states. In Maine it was first discovered in Kittery in 2003. It has spread and now has been found as far up the coast as Bristol. The invasive insect has been found at two other state parks, Ferry Beach State Park in 2008 and at Wolfe’s Neck Woods State Park in Freeport last summer.

HWA was first discovered at Vaughan Woods in December 2010 by a volunteer. In March of this year, an inventory effort supported by about 40 volunteers detected no more of the invasive insect, Kanoti said. Later this spring, in surveys targeted along waterways, MFS Entomology Technician Wayne Searles and Park Manager Glenn Dochtermann found additional HWA in the park.

“Based on the survey results, less than 2 percent of the trees in the overall stand are infested,” Kanoti said, “but the infestation is concentrated along the streams that go through the park.”

The oval-shaped lady beetle, no more than one-sixteenth of an inch in size and covered with golden hairs, is “a tiny lady beetle with a big appetite for adelgid,” the forest entomologist said.

Originally from Japan, the beetles being released are reared in laboratories in the United States. The Maine Forest Service and Maine Bureau of Parks and Lands have been successful in getting support from Maine Outdoor Heritage Fund, USDA-APHIS and the local public to help in this bio-control effort.

The beetles will be released in hemlock trees located along a feeder stream in the park that leads to the Salmon Falls River.

Emphasizing the threat of HWA to Maine hemlocks, the importance of public awareness about the threat, and the need to report possible findings, Kanoti said that a well-established infestation was reported just this week on a 30-acre site on the Georgetown peninsula. The infestation was apparently present for at least 10 years before being reported. The hemlock trees on the site already are declining, the forest entomologist said.

“We know there are several well-established populations on mid-coast peninsulas,” Kanoti said. “We encourage landowners to contact the Maine Forest Service if they think they may have adelgid on their hemlocks.” The sooner infestations are detected and reported, the more options are available to manage the situation, she said.

For more information, contact Allison Kanoti, MFS forest entomologist, at (207) 287-3147 or by email at:

For more information about hemlock woolly adelgid, go to:



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