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Photo of Route 72 Circle in Burlington County - Click to enlarge
For Immediate Release: July 19, 2007
Contact: Lynne Richmond
(609) 633-2954

(TRENTON) – A continued rise in the acreage of trees defoliated by gypsy moth caterpillars will require a renewed commitment from state and local officials to avoid a repeat next spring of the damage seen this year, New Jersey Agriculture Secretary Charles M. Kuperus said today. 

“Gypsy moth caterpillars are a major nuisance to homeowners and in formulating a treatment plan, we will keep in mind the health and safety of the general public,” said New Jersey Secretary of Agriculture Charles M. Kuperus. “We will be working with the Department of Environmental Protection to determine our treatment options for next year and will utilize every method available to us to protect the state’s trees from the destructive gypsy moth caterpillar.  We also will work with federal and other lawmakers to help secure funding sources for the suppression program.”

More than 320,000 acres of trees were defoliated by gypsy moth caterpillars this past spring, the highest amount since 1990, when there were more than 431,000 acres of trees experienced leaf loss.

The number of acres defoliated more than doubled this year from last year’s total of 125,743.  The increase was due to a rapid population build-up after dry spring weather kept a beneficial fungus disease dependent on moisture from naturally killing off the gypsy moth caterpillars.  The fungus, Entomaphaga maimaiga, had previously helped New Jersey officials control the gypsy moth population.

“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 Secretary Kuperus.  “We will work closely with municipal officials over the next several months to plan how we can slow the spread of gypsy moth caterpillars to protect our forested areas.”

This fall, municipalities with heavy infestations of gypsy moths, as delineated by this summer’s aerial defoliation survey, will be contacted and asked if they wish to have a gypsy moth egg mass count.  This is done to determine if the infestation will continue and what areas qualify for the spray program.  If the residential or recreational forest has an average of more than 500 egg masses per acre, and is at least 50 acres in size it may qualify for participation in the cooperative gypsy moth suppression program.   Municipal participation in the aerial spray program is voluntary.

This year the United States Forest Service provided $1.5 million in 50 percent cost reimbursement funds to municipalities participating in the Department of Agriculture Gypsy Moth Aerial Suppression Program.  This year, 34 municipalities and five agencies in 11 counties participated in the program.  A total of 62,500 acres were treated in those areas with the insecticide Bacillus thuringiensis, or Bt. Bt is a non-chemical, “minimal risk” insecticide that only kills caterpillars. It does not harm other insects, animals or humans. It lasts only five to seven days before being broken down by natural forces.

A total of 124 municipalities in 19 counties experienced 320,610 acres of defoliation -- much of it severe -- from gypsy moth caterpillars this year, compared with 15 counties and 69 municipalities last year. The hardest hit counties were Sussex and Burlington.  Sussex County had the most acres defoliated with 96,655 acres.  However, Burlington had the largest number of acres severely defoliated at 86,855 acres. Counties that did not have gypsy moth defoliation last year, but registered damage this year were Bergen, Essex, Morris, and Passaic.

Two to three consecutive years of significant defoliation (defined as 75 percent or more) can kill an otherwise healthy tree. However, any gypsy moth defoliation can make trees more susceptible to other damage that can lead to the death of the tree.   Oak trees are the preferred host for gypsy moths, but the caterpillars can be found feeding on almost any tree in the vicinity.

In high populations, gypsy moths can blow 15 miles during storms, spreading into untreated areas.  Each year, since 1970, gypsy moth caterpillars have caused varying degrees of defoliation -- between 1,910 and 800,000 acres of forest land.  Past research has shown that repeatedly defoliated forests can expect oak tree mortality varying between 15 to 65 percent.  Department of Agriculture and Environmental Protection staff are monitoring selected sites in NJ to assess current levels of tree loss.

To access the 2007 New Jersey Gypsy Moth Aerial Defoliation survey and for more information on New Jersey’s gypsy moth suppression program, visit:   Also, for national gypsy moth material, visit