Gypsy Moth Infestation May Kill 17,000 Acres of Trees in New Jersey

NEWARK, July 19 — Gypsy moths, which gnawed their way through a number of mid-Atlantic states this spring, stripped the leaves from trees over more than 320,000 acres in New Jersey, the worst infestation since 1990, state agricultural officials said on Thursday.

About 17,000 acres of trees were expected to die this year after this spring’s infestation.

“The loss of trees from gypsy moth damage is more than the loss of our state’s beautiful landscape — it is an environmental threat for trees’ role in filtering the air and providing a habitat for many animals,” said Charles M. Kuperus, the state secretary of agriculture.

Mr. Kuperus, who described areas of devastation after flying over parts of New Jersey last month, said the greatest toll was in Sussex County, in the state’s northwest corner, and Burlington County, in the south, both heavily wooded regions. Damage statewide is more than twice the 125,743 acres that were hit last year.

The gypsy moth caterpillar feeds primarily on oak leaves — the official state tree is the red oak — and agriculture officials say that if the gypsy moths eat 75 percent of a tree’s leaves for three consecutive years, the tree will probably die. Conifers can be killed by just one year of defoliation.

Gypsy moth damage fluctuates yearly, and as recently as 2003 the caterpillars defoliated fewer than 6,000 acres in the state. But this year spring rains failed to arrive in time to encourage the growth of a fungus that is one of the best natural enemies of gypsy moth caterpillars.

New Jersey sprayed 62,500 acres with the insecticide Bacillus thuringiensis, or Bt.

The $40-per-acre cost of the spraying is split between the federal government and the towns where it takes place. Towns are not required to spray, however.

State agriculture officials also wanted to use another pesticide, Dimilin, but the Department of Environmental Protection objected because of concern over its possible effect on crustaceans.

After the state collects more information on the number of eggs that will turn into next year’s caterpillars, it will decide what municipalities are eligible for spraying next year. About five municipalities declined to be sprayed, and some, including Jackson Township in Ocean County, suffered substantial damage this year, officials said.
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