Gypsy Moth Aerial Spraying Update (DATCP)

WHAT: Gypsy moth aerial treatments by the Wisconsin Department of Agriculture, Trade and Consumer Protection’s Gypsy Moth Slow the Spread (STS) Program. The STS aerial program for 2018 consists of 36 treatment sites, involving approximately 90,000 acres across 14 counties in western Wisconsin. The Wisconsin Department of Natural Resources’ Suppression Program is also treating 7 sites in Dane County totaling 485 acres.

WHEN: Tuesday, 22-May-2018, weather permitting.

WHERE: Select sites in Grant, Green, Lafayette, Dane, Vernon, Crawford, and Eau Claire counties. A progress chart and maps of treatment sites can be viewed online at

WHY: The treatments are necessary to control the spread 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: The first Btk treatments will begin in the previously mentioned counties covering 15 sites. Most sites may have more than one treatment planned and will be treated again on a later date.

TREATMENTS: Planes will apply Foray 48B, which is approved for use in certified organic production or food processing by the Organic Materials Review Institute. The insecticide contains Bacillus thuringiensis var. kurstaki or Btk. Btk is a naturally occurring soil bacterium that is poisonous to gypsy moth caterpillars when consumed. Btk breaks down in sunlight within a few days.

OTHER DETAILS: Applications can start as early as sunrise and will continue until the day’s plan is complete and as weather conditions allow. Treatment applications require calm winds, high humidity, and no precipitation.

The planes are loud and will fly low, just above the tree canopy.

Spraying does not affect organic certification.

The insecticide is not toxic to people, bees, animals, birds, or plants.

People who have allergies may wish to stay indoors or leave the area until treatments are done. Pets or livestock may be frightened by the noise of the low-flying planes, so keep them indoors or monitor them.

Most sites will receive a second application of Btk about 7–10 days after the first application.


Treatment updates will be available as a recorded message on the toll-free hotline 1-800-642-6684, press 1. You also can get instant updates by connecting with us on Twitter ( or Facebook ( You can also send an e-mail to