The New Jersey Department of Agriculture (NJDA) this year wants to treat 13,712 acres of residential and county-owned properties in five counties – including Burlington – to combat the tree-killing Lymantria dispar dispar, otherwise known as the gypsy moth.
The recommended treatment areas constitute a significant increase over last year’s 1,400 acres because of the lack of treatments by the states near the northwest border as the moth travels by wind and a dry summer that made the sporadic E. maimaiga (a 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 Jan. 9 to outline its 2025 Aerial LDD Suppression program. Egg mass surveys were conducted from August to December last year. With participation by the affected municipalities – which also include Cape May, Passaic and Morris counties – the program will take place in May and June. Participation is voluntary.
To qualify, 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 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 more.
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 and other North Jersey counties. That was an approximate 80% reduction from what was treated in 2016. The moth 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. And any LDD defoliation can make trees more susceptible to other damage that can lead to their deaths. Oak trees are the preferred host for LDD, but the caterpillars can be found feeding on almost any tree.
For more information on the moth suppression program, visit www.nj.gov/agriculture/divisions/pi/prog/gypsymoth.html. For national LDD material, go to https://www.aphis.usda.gov/aphis/resources/pests-diseases/hungry-pests/the-threat/spongy-moth.
