Gypsy moth caterpillars damage thousands of acres in N.J.

Posted: July 28, 2013

About 2,900 acres of trees in New Jersey - nearly three times the number affected last year - have been defoliated by gypsy moth caterpillars, according to a statewide aerial survey released Friday.

But the number is small compared with years such as 2008, when more than 339,000 acres were damaged by the leaf-eating invasive pests, state officials said.

"While we have seen very low gypsy moth populations over the last few years, we must continue intense surveillance as well as treatment to suppress this damaging insect," state Secretary of Agriculture Douglas H. Fisher said.

The recent survey - conducted in late June and early July - showed that 2,887 acres in 51 municipalities in 17 counties received moderate to severe damage, officials said.

Fifty-three acres were affected in Camden County, 23 in Gloucester County and six in Burlington County. Tree damage also was found in Atlantic, Bergen, Cumberland, Essex, Hunterdon, Mercer, Middlesex, Monmouth, Morris, Ocean, Passaic, Somerset, Sussex and Warren Counties. The most damage was found in Bloomingdale Borough and West Milford Township, both in Passaic County, which had a total of 1,087 acres of trees heavily damaged.

In 2012, 1,068 acres of trees in 21 municipalities in 10 counties were defoliated by gypsy moths - the lowest recorded defoliation since the department's Gypsy Moth Suppression Program began in 1970.

"Gypsy moth populations depend on conditions like weather and other factors," said Lynne Richmond, a spokeswoman for the state Agriculture Department. "We had a fairly wet spring that promoted the growth of fungus that's detrimental to them" - another factor in holding down the population, which has collapsed over the last several years.

Gypsy moth caterpillars lay their eggs on trees and emerge in May and early June. This year, no spray program was needed because of low populations.

The state has been monitoring the bugs and "aggressively responds when it sees their population getting higher," Richmond said. To qualify for the spray program, a residential or recreational forest must have an average of more than 500 egg masses per acre and be at least 50 acres in size. A single egg mass contains up to 1,000 eggs.

"We plot out spray blocks and propose them to the municipality in January," Richmond said. The towns pay for the program and "determine if they want to be part of it."

Contact Edward Colimore at 856-779-3833 or


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