The Pennsylvania Department of Conservation and Natural Resources, Bureau of Forestry, (DCNR) - annually conducts an aerial gypsy moth suppression project for private residential landowners throughout Pennsylvania. This program is conducted and cost shared in cooperation with participating counties or other local municipalities and receives partial funding from the USDA Forest Service. To qualify for this program, your property must meet the requirements detailed below, and you must be willing to assume the responsibilities indicated.
Objective - DCNR's sole objective under this program is to prevent gypsy moth caused defoliation in treated forest residential areas from exceeding 30% on 80% or more of the highly favored host trees.
Because of the limitations inherent in the insecticides available and the degree of gypsy moth infestation in Pennsylvania, it is not economically feasible, nor is this program designed to eradicate the insect from any part of the Commonwealth. In addition, because of the variation in insect tolerance levels of individual people, the nuisance problem caused by larval populations may not be reduced sufficiently to placate all landowners serviced even though the foliage protection objective is met.
Minimum Spray Block Size - The minimum spray block size for an area to qualify to be sprayed must be at least 25 acres. These 25 acres may be made up of more than one qualifying property as long as when in total the area meets the minimum 25 acre requirement.
Qualifying Areas - Only forested private residential sites containing trees 25 feet or more in height qualify for this portion of the program. These sites must have at least 50 percent of the surface area, when viewed from above, covered by the crowns of these trees. Twenty percent or more of this crown cover must be made up of tree species which are highly favored by the gypsy moth. Highly favored species include apple, aspen, basswood, beech, birches (gray, white, and river), boxelder, hawthorn, larch, oaks (all species), willows, and witch hazel. The site must have a dwelling located within or no more than 200 feet from the forest. The spray block to protect this site will be designed to provide treatment to all forested areas within 500 feet of the dwelling. The spray block will be designed in this manner to facilitate aerial spraying regardless of how large or small the landowner's property actually is. Spray blocks will not be custom designed to accommodate property boundary lines. Neighboring residential properties where all the landowners desire treatment will be combined into a single block whenever possible.
Non-Qualifying Areas - Properties with no dwelling do not qualify for this program. Residential properties with only scattered ornamental trees and shrubs or any property with trees that are readily accessible to ground spray equipment do not qualify for this program. Also, areas that contain any nontarget organisms that would be adversely affected by spraying or areas which are unsafe for aerial spraying because of obstructions or terrain will not be considered.
The proposed treatment areas must contain at least 250 healthy, current-season gypsy moth egg masses per acre or, if there are less than 250 egg masses per acre, there must be a reasonable expectation that high numbers of gypsy moth larvae will be blown into the area next spring. Only areas within one air mile of a heavily infested ridge qualify in the latter respect.
Insecticide - A biological insecticide, Bacillus thuringiensis, is the only spray material that DCNR will use on private residential lands under this program. DCNR will select the rate of application based upon gypsy moth population density and health with the highest rate used on the heaviest, healthiest populations. Because Bt is a biological insecticide whose effectiveness can be affected by weather conditions during and after application, DCNR does not guarantee the degree of control.
The Pennsylvania Gypsy Moth Suppression Program uses the bacterial insecticide, Bacillus thuringiensis var. kurstaki, or BT, to control young gypsy moth caterpillars. It works by interfering with the caterpillar's digestive system. Contractors are hired to spray the material on forested areas using an airplane during gypsy moth outbreaks. BT will only affect caterpillars of moths and butterflies that feed on it by consuming foliage. It is not toxic to other insects, mammals, birds, or fish. It only remains on the leaves for about ten days after application.
How safe is Bt for humans?
After 40 years of testing and widespread use, Bt has demonstrated minimal hazards to mammals, birds, fish, beneficial insects and other non-target organisms. To ensure the continued safety of Bt for the public, the EPA administers an extensive system of regulatory safe- guards. These include requirements for mammalian and environmental toxicology testing of the Bt active ingredients and formulated Bt products. Quality control procedures are also in place to ensure the safety of each batch of the Bt product.
As part of its regulatory function, the EPA recently con- ducted a reassessment of Bt safety. This reassessment confirmed earlier findings: "...the lack of any reports of significant human health hazards of the various Bacillus thuringiensis strains..."
(EPA document #EPA738-R-98-004, March 1998).