HARRISBURG, Pa - The start of aerial spraying of state woodlands to combat spongy moth (Lymantria dispar dispar, formerly known as the gypsy moth) populations has begun in many sections of Pennsylvania, according to a news release.
“Suppression efforts are underway as the caterpillars emerged and begun feeding,” Dunn said.
“Aerial suppression is needed to keep this invasive pest in check and protect our native forests from defoliation, with oaks being one of its favorite host. Keeping our forests healthy is of paramount importance, to protect all of the values our forests provide, including recreation, habitat, timber, clean air and clean water.”
Not actual image - Aerial spraying
The news release said that the suppression program is conducted with the goal of minimizing defoliation so that trees do not become stressed and succumb to disease, other insect pests, or drought.
Aerial spraying will be conducted by two helicopters and six fixed-wing aircraft.
Progress of the treatment program can be followed using the DCNR Spongy Moth Daily Spraying Status GIS Map, which shows the location of all 185 spray blocks.
In 2023, spongy moth defoliated 441,819 acres in Pennsylvania, according to the news release.
DCNR’s Bureau of Forestry will oversee the spraying of 185 sites totaling 227,820 acres.
Included will be portions of 12 state forests and 18 state parks, and one federal property in 20 counties located in southcentral, central, northcentral, and northeast Pennsylvania.
In 2023, a total of 290,000 acres were treated.
In addition to DCNR’s spray program, the Pennsylvania Game Commission will also be conducting an aerial spray program in 2024 on approximately 124,000 acres of State Game Lands, according to the news article.
State parks to be sprayed include:
Bald Eagle, Centre County
Big Spring, Perry County
Colonel Denning, Cumberland County
Colton Point, Tioga County
Hyner View, Clinton County
Kings Gap, Cumberland
Leonard Harrison, Tioga County
Little Pine, Lycoming County
Ole Bull, Potter County
Penn Roosevelt, Centre County
Poe Paddy, Centre County
Poe Valley, Centre County
Prince Gallitzin, Cambria County
R.B. Winter, Union County
Ravensburg, Clinton County
Reeds Gap, Mifflin County
Sand Bridge, Union County
Whipple Dam, Huntingdon County
Federal property to be sprayed include:
Grey Towers National Historic Site, Pike County
“These destructive, invasive insects go through cycles where outbreaks generally occur every 5 to 10 years,” DCNR Forest Health Manager Rosa Yoo said. “We are entering in our fourth year of the outbreak cycle, and egg mass surveys from last year determined the need for suppression efforts again this year. The good news is that we observed a decline in spongy moth defoliation from 850,000 acres in 2022 to 440,000 acres in 2023, signifying a decline in spongy moth populations and the importance of these suppression activities to help continue to reduce spongy moth populations.”
Targeted sites are determined by surveys of egg masses and other indicators across the state indicating high population levels that have the potential to cause major defoliation.
Feeding while in the larval -- or caterpillar -- stage, the insect usually hatches and begins feeding from mid- to late April in southern Pennsylvania, and in early to mid-May in the northern part of the state.
Oak, apple, sweet gum, basswood, birch, aspen, and willow trees are most affected by the spongy moth, according to the news release.
DCNR Bureau of Forestry experts note the state’s oak stands are especially vulnerable to infestations.
The news release says that a tree begins to significantly suffer when 30 percent or more of its leaf surface is lost, and when left untreated, heavy infestations over two to three consecutive years can result in tree mortality. They also said that oak mortality leads to a loss of timber resources, a decrease in the carbon sequestered by our forests, and negatively impacts the habitat quality for many of our native species.
Not only are oaks an important mast species for wildlife, but oaks host a significant number of native insects and invertebrates as well.
The insecticides, tebufenozide or Bacillus thuringiensis subsp. kurstaki, are applied to emerging foliage and must be ingested by young caterpillars, according to the news release.
The news release also said these insecticides are subject to State and Federal environmental review and are deemed safe for use. They are commonly used in agriculture, they said.
Begun in 1972, the forest insect spray program is a cooperative effort among DCNR and the U.S.D.A. Forest Service’s Forest Health Protection Unit.
The Lymantria dispar dispar was introduced to North America in 1869 at Medford, Massachusetts, where it was used in a failed silk-production experiment.
The spongy moth first reached Pennsylvania in Luzerne County in 1932, and since then has infested every county.
Visit DCNR’s website for more information about spongy moths and DCNR’s suppression program.