ALBANY - 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 told The Associated Press Wednesday.
But the discovery of an emerald ash borer infestation in the Dutchess County 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.
An emerald ash borer on a penny
(Photo — Howard Russell, Michigan State University, Bugwood.org, via Wikipedia Commons)
"It's rare that infestations are found this early," said Nate Siegert, a U.S. Forest Service entomologist who has been working in Rhinecliff this month. He credited state Department of Environmental Conservation foresters for taking steps that led to the discovery.
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. Borer infestations were found in western New York in 2009, but experts say the Hudson Valley colony could have started years before that, possibly after catching a ride across the state in a load of wood.
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.
New York became a leading edge for research and control efforts after a major infestation was discovered on the west shore of the Hudson in 2010, about 150 miles east of colonies discovered elsewhere in New York since 2009.
Researchers set out purple traps and stripped bark from trees last year, eventually mapping finds of beetle larvae in a 225-square-mile area running north from just below Kingston, bounded on the east by the river and parts of the Catskills in the west.
Jeff Rider, a DEC supervising forester, said 28 "trap" trees on the east shore were also girdled - stripped of a band of bark - to attract any beetles that may have made it across.
Three of those trees just below the Kingston-Rhinecliff Bridge about 25 miles from the Connecticut and Massachusetts borders were found with small infestations in March, he said. That sent researchers ranging through a 3-mile radius around each, taking samples from 78 other ash trees. Rider said none of those trees was infested, but an additional 100 trees have now been girdled in the area.
He said plans are being made to quarantine moving ash material in Dutchess County, but he thinks that may be limited to particular towns, not entire counties like across the river. People can be fined for moving firewood 50 miles beyond its origin, a regulation meant to thwart ash borers and other invasive pests.
Rider thinks the latest infestation involved adults that crossed the river during last summer's flying season.
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," Rider said. "We're just trying to buy them some time."
Siegert said traps in New England showed no sign of the borers this past season, but that doesn't mean some haven't arrived.
"I think we'd be remiss to think it's completely clean, that there isn't something simmering beneath our radar," he said.
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."