Emerald ash borers take toll

The emerald ash borer beetle, an invasive species from Asia, did more damage to Wilton’s ash trees this year than in previous years, and the local tree warden predicts it will get worse.

“We haven’t seen the worst of the emerald ash borer. It is just getting to the peak of infestation in Wilton,” said arborist and Wilton tree warden Lars Cherichetti.

There are more trees dead than last year. This year, the beetles killed 96 trees, compared with 91 in 2016, he said.

The drought and the windstorms contributed to the deaths.

“We also struggled with two years of drought, and the weakened trees have died and are now becoming a problem,” Cherichetti said, adding that a lot of the trees that fell onto town roads during the Nov. 19 windstorm were dead trees on private land.

It was a bad storm, said Capt. Robert Cipolla of the Wilton Police Department.

“A lot of trees and wires were down and and we had several road closures as a result,” Cipolla said after the storm.

The emerald ash borer is a pest in the Northeast, but a pretty one. It is known for its iridescent green shell that makes it look like a gem from a piece of costume jewelry.

The emerald ash borer is an invasive species native to Asia, first noticed in the United States in 2002 in Michigan. It has since spread north into Canada, south to Tennessee, west to Minnesota, and east to New York and now Connecticut.

Cherichetti said the beetle was detected in Wilton in the summer of 2015 by monitoring wasps that feed on it.

Beetle eggs are laid in bark crevices. Much of the damage to the trees is done by the larvae, which feed on the trees’ conductive tissues, just under the bark, leaving what the Connecticut Agricultural Experiment Station describes as “tightly winding serpentine galleries” that can “very quickly stress and girdle an ash tree.”

They mature over the winter and the adults emerge — metallic green and about a half-inch long — to live about a month in the summer, feeding on ash foliage.

Based on a quick survey of roadside trees, Cherichetti estimated that “we have on the order of 500 trees we will have to deal with.”

When asked about town-owned properties, he said the town forest in particular has a few ash trees, mostly in the southern part near Branch Brook. Other parts of the park are dominated by oaks, beech and maples.

“We will certainly notice the ash trees’ absence in areas where they are common,” he said.

Although there are no accurate surveys, Cherichetti thought 10% to be a good estimate of how much of the tree canopy is made up of ash trees.

Cherichetti said people with ash trees on their property should consider whether to prevent infestation with insecticides or take trees down.

“It is possible to treat a tree for eight to 10 years and still [cost] less than it would be to remove the tree, particularly if the tree is difficult to access with equipment,” Cherichetti said.

“Insecticide works as a preventative and is injected into the tree’s trunk so the chemicals are applied directly where needed.”