Experts predict another year of defoliation from the spongy moth

Experts predict another year of defoliation from the spongy month
Published: May. 16, 2022 at 8:42 AM EDT
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BURLINGTON, Vt. (WCAX) - The spongy moth, formerly known as the gypsy moth, has returned for the season and is looking for food in the trees.

Last year, the insects caused a significant amount of defoliation in Vermont and New York.

The Vermont Department of Forests, Parks and Recreation says it’s hard to predict the outcome, but they expect another year of defoliation.

The spongy moth egg masses have hatched again.

“It goes through these cyclical outbreak patterns where they defoliate trees,” said Josh Halman, with Vermont Forests, Parks and Recreation.

Halman says last year, these pests were very noticeable. Large outbreaks created residential plights and large sections of forest went bare. Halman says their survey plots are pointing to another tough year.

“Evidence from those says we can expect defoliation again this year,” said Halman.

They have nine annual survey plots in the state, seven in the Champlain Valley and two in southeastern Vermont.

They take inventory of the number of egg masses on trees in the fall to get a gauge on next year’s numbers.

“One of the main controls for this caterpillar is a fungus known as Entomophaga maimaiga,” said Halman.

Halman says part of the reason last year’s outbreak occurred was that a lingering drought didn’t allow the fungus to grow.

We are not in a drought now, meaning they hoping nature runs its course.

“The hope is that that fungus will be reactivated significantly, and that should provide significant protection against the caterpillars,” said Halman.

But on the residential side, Halman recommends wrapping trees in burlap. To trap the caterpillars, he says duct tape can work, but sometimes it isn’t sticky enough.

“Every day the homeowner should look in that burlap, look for those caterpillars and scrape them into soapy water, and once they have died, you can dispose of them,” said Halman.

It won’t stop all of them but will help locally.

The state has no plans to spray, as Halman says they haven’t sprayed for the spongy moth in 30 years.

There is also no threat to humans, though they are a nuisance. Halman says really it’s about tree health and he knows defoliation can be demoralizing, but it will end.

“The defoliation from spongy moth, especially when it’s on a large scale, can be demoralizing and are a mess and a nuisance, but the important note is that these outbreaks come to an end. They don’t last forever. They last for about three years-- can go as long as five years-- but they will come to an end. Our trees are resilient and in large part, we will be able to recover from this,” said Halman.

Halman also wants to remind folks that these sorts of outbreaks happen cyclically and our forests have proven to be quite resilient even with defoliation as long as other resources like water are present for them.

Click here for more information on tree health.

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