Vigorous efforts are underway to thwart two Asian beetles that now pose a threat to Connecticut’s ash trees and at least 10 of its other hardwood trees, with the state’s sumptuous shade maples among them.
The Asian emerald ash borer, first documented in this country in Michigan in 2002, is believed to have arrived as a stowaway in a cargo of wood packaging materials from China in the 1990s.
The larger Asian longhorned beetle, which also entered this country in the 1990s, attacks maple trees among other hardwoods such as elm, poplar and birch. Like the ash borer, it destroys a tree’s circulatory system. It can kill a tree in three to five years.
Connecticut has 24 million ash trees and 290 million maple trees, according to Chris Donnelley, an urban forester with the state. Roughly 239 million of them are the red maple trees valued not only for their fall color but also summer shade.
“Connecticut without maples would be a pretty dull place in the fall,” observed Rose Hiskes, diagnostician and horticulturist at the Connecticut Agricultural Experiment Station in Windsor and New Haven.
The ash borer digs into the bark of a tree to lay its eggs. The larvae, which then feed on the layers of the bark, kill a tree by destroying its circulatory system. The circulatory system brings nutrients to a tree’s upper branches and leaves.
Infestation by the ash borer, which has the lifespan of a year, can kill a tree within five years, Hiskes, said. According to the U.S. Department of Agriculture, tens of millions of ash trees have already died or become heavily infested by the somewhat irridescent beetle.
First detected in the 1980s, yellow ash disease has already weakened many ash trees, making them more vulnerable to the insect. The ash disease results from a microbe that, like the beetle, invades a tree.
Hiskes said the emerald ash borer has been detected 13 miles from Connecticut’s border on the campus of Holy Cross College in Massachusetts and that the ash borer was detected 25 miles from the state line this March in Rhinebeck, New York.
Of the two beetles, she said the ash borer can fly a significant distance, and that one beetle can lay as many as 90 eggs—one, perhaps, per tree.
“The Asian longhorned beetle moves out so slowly,” said Hiskes, terming its infestation of Connecticut trees an ‘if.’ “We will get the ash borer, I know,” she said, terming its presence in the state a ‘when.’
This summer, state agencies have distributed 540 large “Barney” traps—so named because of their purple color—to monitor trees for the presence of the ash borer.
According to the Department of Energy and Environmental Protection’s website, the “Barney” traps are covered with a non-noxious oil that attracts the beetle. The devices themselves are covered with a sticky substance that then traps the beetles, although it poses no danger to birds and other animals.
Also, the state and its agricultural experiment station has launched a broad educational effort to get the word out about the danger posed by the beetles and, for three years, has surveyed a random sample of garden centers and nurseries to check for the presence of the insects there.
Hiskes is especially concerned that wood infested by the larvae of the ash borer will appear at campgrounds. She also urges persons to use only local firewood and not move firewood between towns. She noted that firewood carried from other locales, such as Western Connecticut, might already contain the ash borer’s larvae. Infestation by the ash borer, she said, typically occurs two to five years before the damage to the tree becomes apparent.
“The larvae are in wood,” she said. “Leave that firewood out over the winter and next June or July the adults come out. “