Lehigh County is cooperating with the Pennsylvania Department of Conservation and Natural Resources-Bureau of Forestry and the USDA Forest Service in a joint effort to spray gypsy moth caterpillars this spring in certain residential and public high-use areas within the county. The areas scheduled for treatment are located in Lynn, Weisenberg, Lowhill, Heidelberg, Washington, Whitehall, North Whitehall, South Whitehall, Slatington, Slatedale and Upper Macungie.

These treatment areas were selected on the basis of surveys and resident requests received last summer. No additional areas can be added at this time.

A biological insecticide, Bacillus thuringiensis var. kurstaki (Bt), which only affects leaf-eating caterpillars, will be used. However, (Bt) may not kill all of the gypsy moth caterpillars. In severe infestations, the percentage of surviving gypsy moth caterpillars may still be sufficient to cause some defoliation and also be a nuisance to the homeowner. Because of this and the variability in control caused by the weather, the results cannot be guaranteed.

The spraying is scheduled to occur sometime in late April to early June depending upon caterpillar and leaf development. Local news channels will carry information on more specific dates. Spraying will be done by aircraft starting daily at daybreak and continue as long as wind and other conditions are acceptable. Evening, weekend and holiday spraying will also be conducted when conditions permit.

Normally, only one treatment will be applied to any particular property. (Bt) has not been shown to be harmful to humans, pets, livestock or gardens. However, it is recommended that you observe normal precautions and remain under cover during the spray. If exposed to the spray, wash with soap and water.

Program standards provide for the treatment of a forested buffer extending no more than 500 feet from residence(s) being protected. Open fields, open areas containing only a few scattered trees and narrow fence rows will not be treated.

Detailed maps of the treatment areas are available for your review at the Commonwealth of Pennsylvania Department of Conservation and Natural Resources-Bureau of Forestry Division of Forest pest management website, dcnr.state.pa.us/forestry/insectsdisease/gypsymoth/.

Landowners within approved spray blocks were individually notified in December, January and February.

Any additional questions regarding the gypsy moth, the insecticide or this program can be directed to Jeffrey Carroll, Penn State Cooperative Extension, Lehigh County at 610-391-9840.