The New Jersey Department of Agriculture (NJDA) is seeking to treat 13,712 acres of residential- and county-owned properties in Burlington, Cape May, Passaic, Morris and Sussex counties this year to combat the tree-killing Lymantria dispar dispar (LDD – formerly called the gypsy moth).
The recommended treatment areas are a significant increase over last year’s 1,400 acres. The reasons for the increase are a combination of the lack of treatments by the states near the northwest border as the moth travels by wind, and a dry summer which made the sporadic E. maimaiga (an LDD moth fungus) less active. More than 7,000 of the recommended treatment areas are in the northwest corner of the state in Sussex County.
“With the moth’s increase in activity, these treatments are critical in helping prevent the spread of this insect and reducing its population in future years,” New Jersey Secretary of Agriculture Ed Wengryn said. “Preserving the valuable trees that are part of New Jersey’s landscape and wildlife resources is an essential element of this program.”
The NJDA held an informational session in West Trenton on Thursday, Jan. 9, to outline its 2025 Aerial LDD Suppression program. Egg mass surveys were conducted from August to December in 2024.
If the effected municipalities in Burlington, Cape May, Passaic, Morris, and Sussex counties participate, the treatments will take place in May and June. Participation is voluntary. To qualify for the program, a residential or recreational forest must have an average of more than 500 egg masses per acre and be at least 40 acres in size. A single egg mass contains up to 500 eggs.
There were 5,100 acres recommended for treatment in 2023, and nearly 9,000 acres in 2022. The previous year, only 50 acres were treated in Cape May County and one municipality in Burlington County opted not to treat 120 acres. There were no areas of the state recommended for treatment in 2019 and 2020. From 2017 to 2018, the NJDA’s program included approximately 3,900 acres of residential and county owned properties in Burlington, Morris, Passaic, Sussex, and Warren counties. That was about an 80% reduction from what was treated in the 2016 program. The population decrease was the result of effective treatments and sporadic E. maimaiga (an LDD moth fungus) activity.
The NJDA and Department of Environmental Protection use Bacillus thuringiensis (B.t.) to combat the LDD moth. It is a biological insecticide that kills the LDD caterpillar when ingested.
Two to three consecutive years of significant defoliation (defined as 75% or more) can kill an otherwise healthy tree. Additionally, any LDD 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 LDD, but the caterpillars can be found feeding on almost any tree.
Regional meetings outlining the treatment plan were held in Cape May County, Burlington County and Sussex County in January.
For more information on New Jersey’s LDD suppression program, visit: www.nj.gov/agriculture/divisions/pi/prog/gypsymoth.html. Also, for national LDD material, visit https://www.aphis.usda.gov/aphis/resources/pests-diseases/hungry-pests/the-threat/spongy-moth.
