Gypsy Moth Surveillance

Current Conditions

Gypsy moth damage in 2011 was unnoticeable, nor were new egg masses observed. No suppression spraying was carried out in 2011, nor is it scheduled in 2012. However, numbers will build sometime over the next 3-7 years as part of the insect's life cycle. This build-up can be rapid when weather conditions over 2-3 seasons are favorable for the insects. For more information on the biology and images of the insect, visit the Department of Conservation and Natural Resources Gypsy Moth site. 2012 Spring surveillance is underway and homeowners are urged to look for signs in May and June, when the caterpillars are active.

Homeowners must make application for assessment each year they believe they have a gypsy moth infestation. A final decision on county participation in the state suppression program and the responsibility for the cost share is determined after an assessment of the problem is made. To request assessment, please contact Diane Oleson by phone or email.

These are the forested residential program criteria. Criteria may change at the discretion of Pennsylvania DCNR. In order to be considered for inclusion in the program the following criteria must be met:

• A minimum count of 250 gypsy moth egg masses per acre or significant danger of blow-in.
• Heavily wooded (over 50% of area near the home covered by tree crown) with a permanent dwelling on the property within 200 feet of the forest.
• Trees on the property composed of at least 25% highly favored species such as oaks that are at least 25 feet in height. Maples, tulip poplar, locust and pines are NOT highly favored species. Lots with a few ornamental trees, or hedgerow type groupings are not considered forested.

• Twenty-three acres are the minimum required to set a spray block, please speak to your neighbors and make application together, because they will become part of a spray block with you. 

• Private landowners who own more than five acres of forestland can also apply for treatment through the Forest Stewardship Program.

There are thousands of different caterpillars living in our yards and wooded areas. Some of the caterpillars frequently mistaken for gypsy moth are the forest tent caterpillar, eastern tent caterpillar, and the fall webworm. Of the three, the forest tent caterpillar acts most like the gypsy moth in that it does not produce a tent, consumes a variety of hardwood species including the oaks favored by the gypsy moth and is given to periodic population outbreaks. Caterpillars found in a large, webbed structure are NOT gypsy moth. The eastern tent caterpillar and fall webworm form large, webbed tents on tree species generally not favored by gypsy moth.

There is No Spraying Planned, What Can I Do?

If you have gypsy moth caterpillars, there are some actions you can take as homeowners. These are described on the DCNR Gypsy Moth Control page. These methods are effective against building populations. If you have too many large trees, you can contact aerial applicators, but a large spray area is required and neighbors will probably want to combine acreage and share the cost.