From the PA dept of Conservation and Natural Resources

DCNR to resume spraying woodlands to combat gypsy moth damage
Pennsylvania will begin spraying again to control gypsy moths, whose population has grown recently despite a virtual collapse in numbers of the woodland insect a few years ago.

“The decision to resume spraying in selected areas follows a second consecutive year of oak defoliation by gypsy moth larvae in the northeast and north- and south-central regions of the state,” said DCNR Secretary Michael DiBerardinis. “Spray areas were selected based on the number and concentration of gypsy moth egg masses, previous defoliation, and ecological, historic, or economic significance.”

DCNR opted not to undertake aerial spraying in 2003, 2004 and 2005 because of sharply declining gypsy moth populations, during which a naturally occurring fungus proved deadly to the insect that defoliates certain hardwoods. In spring 2002—at a cost of nearly $1.5 million for insecticide and aerial application—DCNR’s Bureau of Forestry oversaw gypsy moth spraying operations targeting 58,641 acres in 18 counties. In 2000, more than 100,000 acres were sprayed in 24 counties.

“Spraying helps contain the widespread gypsy moth damage we have seen in the past, but the major controlling factor is, and will continue to be, the prevalence of a fungus in our woodlands,” said State Forester Dr. James R. Grace. “Thanks largely to the gypsy moth’s natural enemy—Entomophaga maimaiga—moth numbers had been way down for several years in most areas of the state.”

Gypsy moth defoliation also has dropped sharply. During spring 2002, a total of 55,798 acres of Pennsylvania forestland were defoliated by the gypsy moth. That was a 76-percent reduction in defoliation from 2001's total of 237,559 acres. In 2000, almost 837,600 acres were defoliated.

“With an eye toward spring 2007, we will, of course, continue monitoring the situation in our woodlands, working closely with county officials, and conducting our annual egg-mass counts from mid-summer into fall,” said Dr. Grace. “Egg masses make it fairly easy to predict what next spring will bring.”

Four helicopters and two fixed-wing aircraft will be used to complete this spring’s aerial suppression project. Again all areas will be treated with the biological insecticide, Bacillus thuringiensis (Bt), comprised of naturally occurring Bacillus spores. In some areas, the bureau also will be applying using Gypchek, a naturally occurring virus specific to gypsy moth larvae.

The 2006 Cooperative Gypsy Moth Suppression Project is expected to last approximately five weeks. Daily updates of spray progress can be viewed here.

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, gypsy moth caterpillars hatch and begin feeding from mid- to late April in southern Pennsylvania, and in early- to mid-May in the northern part of the state. Oak, sugar maple, beech and aspen trees are affected the most by the forest pest.

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 leaves are lost.

Forest insect spray programs are a cooperative effort among DCNR’s Bureau of Forestry, county and municipal governments, and the U.S. Department of Agriculture Forest Service's Forest Health Protection Unit. County and municipal governments share the cost of treating private residential and local government-owned lands for gypsy moth suppression.

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.

For more information on insect pests and other forestry topics, visit DCNRs’s web site at www.dcnr.state.pa.us (click on “State Forests).