Gypsy Moth Spray plans from the WI Dept of Ag

Post Date:05/12/2016 1:24 PM


WHAT: Gypsy moth aerial spraying by the Wisconsin Department of Agriculture, Trade and Consumer Protection’s Gypsy Moth Slow the Spread (STS) Program. The STS aerial program for 2016 consists of 86 treatment sites, involving approximately 240,000 acres in 19 counties, mostly in western Wisconsin.

WHEN: Friday, May 13, weather permitting.

WHERE: Select sites in Chippewa, Dunn and Eau Claire counties. A spray progress chart and maps of spray sites can be viewed online at

WHY: The spraying is 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 seven spray blocks. Most sites may have more than one treatment planned and will be sprayed 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: Spraying can start as early as sunrise and will continue until the day’s spray plan is complete and as weather conditions allow. Spraying requires calm winds, high humidity and no precipitation.
The planes will fly low, just above the tree tops. They will be loud. Spraying does not affect organic certification.
The insecticide is not toxic to people, bees, animals, birds and plants. People who have allergies may wish to stay indoors or leave the area until spraying is done. Pets or livestock may be frightened by the noise of the low-flying planes, so keep them indoors or keep a close eye on them. Most sites will receive a second application of Btk about three to 10 days after the first application.

Spray 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

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