FREEPORT — Wolfe’s Neck State Park has an unwanted visitor.

It’s small, white, fluffy and likes trees, specifically hemlocks. So much so, that it kills them.

The hemlock woolly adelgid, or HWA, is a tiny cotton ball-looking insect that is attacking hemlock forests along Maine’s coast.

In a move to subvert the invasive species, the Department of Agriculture, Conservation and Forestry has released 1,700 predator beetles at Wolfe’s Neck and two other state parks: Vaughan Woods in South Berwick and Ferry Beach in Saco.

The small, black beetles, known as Sasajiscymus tsugae, will also be released into other areas in the state in the coming months, including Cape Elizabeth and Wiscasset.

The effort will be supported by a cooperative agreement between the state and the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service Plant Protection and Quarantine program.

While the predator beetles have been released into specific areas, the state has to contain them and keep close tabs on where the insects are moving, department spokesman John Bott said.

“What we try to do is get the public involved,” Bott said. “This is one thing where the public really has a role. We’re really can’t do this without people being on lookout and being aware.”

Managing the HWA is vital to the long-term health of hemlock trees in Maine, Bott said, noting that although it’s best to catch invasive species as soon as possible, this particular insect has already taken hold.

The species injects toxic saliva while sucking sap out of the trees, causing the infested branches to dry up and the leaves to turn grayish-yellow and drop from the trees. Infested trees are more likely to succumb to diseases and wood-boring insects, which makes the weakened trees more susceptible to being toppled by strong winds, according to the department.

While other methods, such as sprayed pesticides, could be used to thwart the aphid-like insect, the state believes unleashing predator beetles is the most effective way to attack them in this circumstance.

The beetles come from a Pennsylvania laboratory and were purchased with money donated by park supporters, including the South Berwick Conservation Commission, and federal grants, Bott said. It’s not completely known how widespread the HWA problem is or how long it will take to manage them appropriately, he added.

Invasive species, such as HWAs and the much more harmful ash wood borer, seen in New Hampshire earlier this year, are often transported by people bringing in firewood or out-of-state plants into Maine gardens, nurseries or greenhouses.

HWA, originally from Japan, has been found in 18 different states, with its first Maine sighting in a Kittery forest in 2003.

At Wolfe’s Neck, forestry staff first found them in 2010 as part of an annual inspection survey.

Will Graff can be reached at 781-3661 ext. 123 or wgraff@theforecaster.net. Follow him on Twitter: @W_C_Graff.

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The Maine Department of Agriculture, Conservation and Forestry is releasing 1,700 predator beetles into Wolfe’s Neck State Park in Freeport to combat the spread of an invasive species known as the hemlock woolly adelgid.

The hemlock woolly adelgid is an invasive species present in forests along Maine’s coast. The aphid-like insect weakens hemlock trees, making them more susceptible to destruction and disease.