HARRISBURG – Preparing for a spring that may bring declining gypsy moth infestations in some counties and stronger populations in others, the state Bureau of Forestry will target 25 counties in its aerial spraying effort to suppress the woodland insect pest.
Gypsy moth numbers are at levels that require 178,382 acres of woodlands be sprayed in the south-central, central and northeastern sections of the state, according to the Department of Conservation and Natural Resources.
“Our aerial and ground surveys showed more than 766,500 acres of woodlands were defoliated last spring by the gypsy moth, with damage decreasing in the south-central section of the state, but increasing in some central and northeastern counties,” said DCNR acting Secretary John H. Quigley.
“Despite last spring’s extensive spraying program, gypsy moth infestations actually increased in some areas, particularly the Pocono Mountain region, where decline or collapse was expected after four straight years of strong populations,” Quigley said.
Statewide in spring 2008, 221,221 acres of private, state and federal woodlands were sprayed in 27 counties. Nearly 65,000 acres in 19 counties were sprayed in 2007.
“Private woodland owners and state forest visitors must remember spraying is a suppression effort, a forest management effort to protect trees from moderate to severe defoliation,” Quigley said. “The gypsy moth will continue its cyclic population with ups and downs. We cannot eradicate the insect; it’s too well established and is here to stay.”
This year, 18 counties elected to enroll 76,759 private acres in the spray program. In 2008, 21 counties enrolled 95,305 private acres after gypsy moth caterpillars defoliated 681,000 acres in 2007. In spring 2007, 11 counties requested 35,900 acres be sprayed.
“Counties and cooperating agencies opt to enroll and share in the costs of treatment in this voluntary program,” said State Forester Daniel Devlin. “Again this spring, the private acres and state lands to be sprayed are concentrated in the northeast and north- and south-central regions of the state where there have been four consecutive years of oak defoliation by gypsy moth larvae.
“We target and select woodlands for spraying based on the number and concentration of gypsy moth egg masses found and previous defoliation, as well as ecological, historic or economic significance,” Devlin said.
Utilizing seven helicopters and four fixed-wing aircraft, the spray program is set to begin in early May and end shortly after May 25, Memorial Day, with 1,017 spray blocks targeted. Dependent on weather, foliage development and caterpillar development, progress of the 2009 Cooperative Gypsy Moth Suppression Project can be tracked online.
Homeowners and other private property owners also can learn more about the gypsy moth, the damage it causes, and small-scale efforts to combat it by visiting a “Frequently Asked Questions” section and other extensive information posted on the Bureau of Forestry’s Web site (click on “Forestry,” then “Gypsy Moth” at right).
“Prior to spring 2006, and thanks largely to the gypsy moth’s natural enemy—Entomophaga maimaiga—moth numbers had been down significantly for several years in most areas of the state and spraying was not necessary,” said Dr. Donald A. Eggen, chief of the bureau’s Forest Pest Management Division. “Spraying helps contain the widespread gypsy moth damage we’ve seen in the past, but the major controlling factor is, and will continue to be, the prevalence of this fungus in our woodlands.”
Counties enrolled in 2009 and private acres to be sprayed are as follows: Adams, 887; Berks, 427; Blair, 126; Centre, 6,556; Chester, 127; Clinton, 1,966; Cumberland, 7,152; Dauphin, 6,303; Franklin, 440; Fulton, 1,364; Lebanon, 3,273; Luzerne, 6,705; Lycoming, 653; Monroe, 201; Perry, 1,018; Pike, 32,132; Snyder, 1,164; and York, 6,265.
In addition, only state parks and forestlands, state game lands and other woodlands will be sprayed in seven counties: Clearfield, Huntingdon, Juniata, Lancaster, Schuylkill, Tioga and Union.
Gypsy moth populations had been dropping sharply since 2000 until spring 2006 when 700,000 acres of woodlands were defoliated as DCNR treated 82,000 acres in eight counties. DCNR opted not to undertake aerial spraying in 2003, 2004 and 2005 amid years of sharply declining gypsy moth populations, during which the naturally occurring fungus proved deadly to the insect that defoliates oaks and other hardwoods trees but will feed on more than 200 species of trees and shrubs.
All areas will be treated with the biological insecticide, Bacillus thuringiensis (Bt), comprised of naturally occurring Bacillus spores which must be ingested by the caterpillar. No chemical insecticides are used.
Forestry bureau experts identify the gypsy moth as one of the most destructive forest pests in Pennsylvania. Feeding while in the larval—or caterpillar—stage, the insect 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, poplar and willow trees are affected the most by the gypsy moth. Older larvae also will feed on confers such as hemlock, pines, spruces and southern white cedar.
When populations peak, the insects may strip trees of foliage, leaving them weakened and susceptible to disease, drought and attack by other insects. A tree begins to suffer when 30 percent or more of its leaf surface is lost.
Forest insect spray programs are a cooperative effort that begun in 1972 among DCNR’s Bureau of Forestry, county governments and the U.S. Department of Agriculture Forest Service’s Forest Health Protection Unit. County governments share the cost of treating private residential and local government-owned lands for gypsy moth suppression. Funding support of the 2009 spray program also is received from the Pennsylvania Game Commission, Department of Corrections, and Department of Military and Veterans Affairs.
The gypsy moth was introduced to North America in 1869 at Medford, Mass., where it was used in a silk-production experiment. The gypsy moth first reached Pennsylvania in Luzerne County in 1932, and since then has infested every county.