Waging a losing battle against an invasive beetle
With the battle lost, the federal government is admitting what everybody knew — the emerald ash borer controls the field.
The U.S. Department of Agriculture announced on Dec. 15 that the USDA’s Animal and Plant Health Inspection Service will no longer try to use federal quarantines to control the spread of the invasive and highly destructive beetle.
Because the borer has now pretty much infiltrated all states east of the Mississippi River, killing about 35 million ash trees from Louisiana to New England along the way, the decision was expected.
“It doesn’t make sense to continue,” said Claire Rutledge, an associate agricultural scientist in the entomology department of the Connecticut Agricultural Experiment Station.
However, now the borer is here, new local fights against it are beginning using biological controls.
Rutledge and other entomologist’s
are releasing three species of tiny parasitic wasps that feed on and destroy the borers’ eggs. The hope is that in a decade or two, when ash trees start to grow back, the wasps will have lowered the beetle’s numbers enough to let new ash trees survive.
Rutledge said there are 18 sites in the state where the agricultural experiment station has released the wasps, including places in Sherman, Kent, Weston and Litchfield. The wasps are wintering over and spreading.
Initial research shows they’re also doing their work to reduce ash borer numbers.
“It seems to be working,” she said. “Those little wasps are doing a bang-up job.“
Alas, the program comes too late for the beautiful, straight-grained ash trees growing alongside town roads or planted for shade in cities - trees whose seeds feed birds and moths, whose wood is great for ax handles, hockey sticks, furniture and flooring, and whose fall foliage adds a dark reddishpurple
swatch to the landscape.
They’re pretty much lost. The emerald ash borer — which is a native to China, Japan, Korea, Mongolia and far eastern Russia — and which somehow showed up in Michigan in 2002 and has spread ever since — is killing them all.
Female borers lay their eggs on ash tree bark. When the eggs hatch into larvae, the larvae bores into the tree and feeds on the inner bark and cambium — the cells between a tree’s wood and its bark — cutting channels into the tree. Those channels girdle a tree, preventing water and nutrients to reach its branches. The infestation can kill a tree within two years.
Woodpeckers then show up to peel away the infested tree’s bark to feed on the larvae. When you see an ash tree with pale yellow stripes and blotches, you know woodpeckers have been at work and that the tree is a goner.
The agricultural experiment station’s researchers found the shiny green beetles in New Haven County, Connecticut in 2012. By now, they’ve spread across the entire state.
“Pretty much every ash tree is gone — 95 to 98 percent are dying,” said Michael McCarthy, Newtown’s tree warden.
“It’s out of control,” said Michel Boucher, New Milford’s tree warden. His town has removed 400 dead ash trees along town roads in the past year, he said.
“They’re all shot,” said Kevin Lindquist, owner of Danbury Tree Pro.
Because ash trees thrive in open spaces, they grow well along roadsides. The cost to towns of cutting down all those dying ashes is another form of emerald ash borer damage - this time to town budgets.
“It will be horrendous,” Newtown’s McCarthy said.
Matt Bartelme, owner of Bart’s Tree Service in Danbury, said that because the emerald ash borer doesn’t spread rapidly on its own — humans moving beetleinfested firewood are its chief means of transport — you can find the occasional healthy ash tree in the woods.
“It’s as if it’s in its own little quarantine,” he said.
Bartelme also said you can track the infestation in the state year by year. Right now, he said, there are still healthy ash trees in coastal towns like Westport and Darien — the borer simply hasn’t spread there yet.
Rutledge, of the experiment station, said that young ash trees’ need for open air and sun may pay off in the future. When big infested, diseased ash trees fall, she said, that will create a hole in the forest canopy, allowing seedlings or trunk sprouts to thrive.
“They’re pretty good truck sprouters,” she said.
Throw in parasitic wasps and there may be hope for an ash tree comeback.
“It’s my prediction,” Rutledge said. “I think there’s a chance for ash trees.”