Gypsy Moth Damage Less Than Expected in N.J.
By Jan Hefler, The Philadelphia Inquirer
Jul. 15–New Jersey officials say gypsy moth caterpillars this year stripped the leaves off thousands of acres of trees — hitting hard in Burlington County, but doing considerably less damage than was expected.
Based on aerial surveys, the caterpillars defoliated nearly 340,000 acres statewide, or about 20,000 more acres than last year, when the infestation was the worst it had been in 17 years. But Joe Zoltowski, coordinator of the Department of Agriculture’s moth control program, said he had anticipated up to 450,000 acres could be affected as the pest population multiplies.
In Pennsylvania, officials say they are seeing fewer pockets of severe defoliation than last year, when the caterpillars ate through more than 680,000 acres of trees.
“The intensity is less — the amount of heavy defoliation — because we had a very cool, wet spring,” said Donald Eggen, forest health manager with the state Division of Forest Pests Management.
Though Pennsylvania’s aerial surveys are not yet complete, Eggen says it appears the weather allowed the caterpillar’s natural predator, a fungus, to thrive and kill many of the larvae.
“Last year, acres and acres of the Poconos were stripped bare. But this year there’s a lot more green in there,” said Eggen. He says there are even signs of collapse in populations in some parts of the state.
Gypsy moths are an invasive species introduced to the East Coast after they were accidentally released in a silk-producing experiment in Massachusetts more than 100 years ago. The fuzzy black caterpillars do all of the damage when they hatch in the spring before they metamorphose into brown moths in the summer. The moths lay eggs on tree barks in the summer; the eggs remain through the winter.
The defoliation weakens the trees, but unless they are attacked by the pest over two or three consecutive years, the leaves often re-grow and the trees may survive. But officials in both states are concerned about the vast numbers of trees that don’t make it.
Last year, 14,000 acres of trees in New Jersey died after defoliation, and officials estimate they could lose more than twice as many, or 31,000 acres, this year from gypsy moths. The tree-kill figures are not expected to be compiled until next month.
“We’re concerned about saving our trees, our oak population,” said Charles M. Kuperus, secretary of agriculture. “When we lose trees, there’s some real impacts to the habitat and the quality of the forest.”
Oak trees, at the top of the caterpillars’ diet, are already threatened by blight, a disease that’s killing off the hardwood species.
Kuperus said the aerial spraying of bacillus thuringiensis has kept the moth populations in check this year. “Aerial spraying is working,” he said.
Eggen agrees that spraying has been effective. Preliminary reports show the caterpillars are denuding trees in the central part of Pennsylvania and at a state forest in the Northeast, near the Delaware Water Gap, where spraying was minimal.
Adjacent to that section is the Kittatinny Ridge in Sussex County, N.J., the hardest hit area in the state.
Kuperus said that last year the largest impact was felt in Burlington and Ocean Counties, but this year these locales fell behind Sussex County.
In Burlington, Pemberton Township officials opted against paying for aerial spraying this year and ended up with more than 10,000 acres of defoliated trees, one of the highest destruction pockets in the county.
In Southampton, the caterpillars munched through 8,000 acres of trees, but local officials said most of these were located in the Pinelands areas that also were not in a spray zone. “We had a tremendous result in the areas we sprayed,” said township administrator Mike McFadden.
New Jersey officials say much of the state forests were left untreated due to cost constraints. While a total of 94,000 acres statewide were treated, only about 1,800 acres out of 98,000 of state forest were sprayed.
Contact staff writer Jan Hefler at 856-779-3224 or jhefler@phillynews.com
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