Franklin County to spray for gypsy moths next spring

July 07, 2007|By DON AINES

CHAMBERSBURG, Pa. - They entered the country through Massachusetts more than a century ago, were first spotted in Pennsylvania in the 1930s and devastated millions of acres of woodlands in the late 1980s and early 1990s.

Gypsy moth caterpillars were back in force this spring, munching their way through hundreds of thousands of acres of oaks, other hardwoods and even coniferous trees. The damage has been done for this year - the caterpillars have metamorphosed into moths - but homeowners whose properties have been infested can take steps now to suppress the voracious insects.

Franklin County is working with the Pennsylvania Department of Conservation and Natural Resources and the U.S. Department of Agriculture Forest Service to spray for the caterpillars next spring. The deadline to apply is Aug. 17, said Sherri Clayton, senior planner with the county's planning department.

"If you had caterpillars this year and defoliation, let us know," Clayton said.


Photos that Clayton took at properties in June showed trees crowded with the caterpillars, or huddled in masses around houses.

The eggs laid the previous year hatch in late April and early May, Clayton said.

"Usually, you don't notice the feeding damage until the caterpillars are larger, late May or early June," said Tim Marasco, a field operations supervisor with the state Bureau of Forestry's Division of Forest Pest Management. By now, the caterpillars have eaten their fill, spun their cocoons, gone through the pupa stage and emerged as moths, he said.

"Once they emerge as adults, all they do is mate, lay eggs and die," Marasco said.

While the life of the adult moth is brief, the eggs are hardy enough to survive winters far more severe than the county has experienced in recent years.

Temperatures of 10 to 15 degrees below zero Fahrenheit sustained over several days are needed to destroy the egg masses, Clayton said. Mild winters and warm, dry springs have aided the gypsy moth comeback, she said.

The final figures are not in, but Marasco said about 1.3 million acres have been defoliated statewide. The problem was worse between 1989 and 1992, with the caterpillars chewing their way through 4 million acres of woodlands in 1990, he said.

In addition to spraying the state forests, there is a residential spraying program that Marasco said dates to the 1960s. Clayton said only about 15 people called about the program in 2006, but there have been more than 300 requests this year.

Those who have experienced defoliation from gypsy moth caterpillars on their residential property and are interested in having it evaluated for the spring 2008 spraying program can contact the planning department by e-mail at

"There's a local cost share. In the past, the county has always paid for that share," Clayton said. "At this point, we don't know what the cost is going to be."

Clayton said the field analysis of the properties will be done in August and September, and landowners will be notified about their eligibility this fall. Bacillus thuringiensis, or Bt, a bacterium that paralyzes the digestive systems of the caterpillars, is used in aerial spraying, she said.

The residential spraying program provides for treatment of a forested area extending no farther than 500 feet from the home being protected, according to the notice from the county. Forested properties without homes, open fields, narrow fence rows and sparsely wooded areas are not eligible.

"This is a suppression program, not an eradication program," Clayton said. The spraying, which takes place after the eggs have hatched next spring, might not kill all of the caterpillars in an infested area.

The planning department also will provide a list of approved aerial spraying contractors for those property owners interested in hiring a company to spray their land with a more potent pesticide.

Native to Europe, Asia and Africa, the gypsy moth was brought to this country in 1868 in a failed experiment to breed a new strain of silk-producing caterpillar, according to Michigan's Gypsy Moth Education Program Web site. Some of the caterpillars escaped, spreading through much of the United States and eastern Canada.

The Herald-Mail Articles