BY GEORGE M. WALSH

Associated Press

The invasive beetle that has destroyed tens of millions of ash trees over the past decade has been found east of the Hudson River for the first time, marking its closest known threat to New England, researchers in New York said Wednesday.

But the discovery of an emerald ash borer infestation in the New York village of Rhinecliff last month may signal a victory in the battle to stem the pest’s spread: Foresters believe the colony was caught less than a year after it got established, a big step given that the beetle can go unnoticed for years.

The larval beetle tunnels under the bark, eventually destroying a tree without any sign until its foliage yellows and dies. The shiny green adults are only about half an inch long and tend to fly well above the ground, making them hard to spot.

Ash trees, prized as a commercial hardwood and a feature in urban plantings, have been ravaged through much of the Midwest and into the mid-Atlantic and Northeast since the Chinese beetle was first discovered near Detroit in 2002.

The main population has been spreading gradually at a pace of about 2 to 3 miles a year, but “satellite” colonies leapfrog ahead, mostly by hitchhiking in loads of logs or firewood.

Forestry experts in New England have been watching for any sign of the ash borer, typically relying on the familiar purple traps.

“They’re gearing up, knowing they’re eventually going to have it,” said Jeff Rider, a Department of Environmental Conservation supervising forester. “We’re just trying to buy them some time.”

Nate Siegert, a U.S. Forest Service entomologist, said traps in New England showed no sign of the borers this past season, but that doesn’t mean some haven’t arrived.

In addition to using trees stressed by girdling to detect infestations, they’re also used as “population sinks” to attract the beetles to known spots where the trees can later be cut down and the larvae destroyed. And researchers in New York are introducing colonies of Chinese wasps that attack ash borer larvae in hopes of controlling the pest in the future.

Chris Martin, the state forester in Connecticut, said the experience of states to the west is helping.

“We’ve had the benefit of watching and learning,” he said, adding that he believes the effort along the Hudson is a “game-changer.”

“In the other states, infestations got out of hand and they threw in the towel,” he said. “Nobody in New England is willing to do that yet.”

Martin said traps will be set out statewide this year. Last year, three-quarters of the state was sampled with 970 purple traps.

“This is a battle worth fighting,” Martin said. “The ash tree resources in New England are phenomenal.”

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