Gypsy Moth Aerial Spraying Update (DNR)

Below is information about the Wisconsin DNR’s upcoming aerial suppression spray for gypsy moths in Dane County at sites in the cities of Madison and Sun Prairie.

WHAT: Aerial spraying for gypsy moth by the Wisconsin Department of Natural Resources Gypsy Moth Suppression Program.

WHENSpraying is imminent in Dane County (Wednesday, April 23, 2018)

WHERE: Seven sites in Dane County, in the cities of Madison and Sun Prairie. Maps of spray sites can be viewed online at

WHY: The spraying is necessary to suppress populations of gypsy moth, a destructive and invasive pest that feeds on the leaves of oaks, maples, crabapple, birch and many other species of trees and shrubs.

PLAN DETAILS: Suppression spray operations are taking place now in Dane County in the cities of Madison and Sun Prairie. The pesticide being used is Foray 48B, which is approved by the Organic Materials Review Institute for use in certified organic production and food processing. The insecticide contains Bacillus thuringiensis var. kurstaki, also known as Btk, which is a naturally occurring soil bacterium lethal to gypsy moth caterpillars when consumed. Btk breaks down in sunlight within a few days.

• Spraying will continue as long as weather conditions are suitable, until the day’s spray plan is complete.
• The planes will be small and yellow, similar to those used for crop dusting. They will fly low and may be loud. The planes will only spray Btk in specific, pre-determined treatment areas.
• The spray is not harmful to people or pets. Residents living in the treatment areas may choose to stay inside with doors and windows closed for the brief period while the spraying is occurring to minimize direct exposure to the spray.
• Pets or other animals may be frightened by the noise of the low-flying planes; keep them indoors or monitor them.
• The spraying does not affect organic certification.
• Btk is not toxic to people, bees, animals, birds or plants.