Gypsy Moth Update: Spraying Operations Concluded for the Day 5-26-2013

GYPSY MOTH AERIAL SPRAY UPDATE – May 24, 2013 – 7:15 a.m.

You will receive e-mail/fax updates as often as necessary until all spraying is completed this year.

WHAT: Gypsy moth aerial spraying by the Wisconsin Department of Agriculture, Trade and Consumer Protection

WHEN: Tuesday, May 28, 2013 weather permitting.

WHERE: Selected sites in Grant, Iowa, La Crosse, Lafayette and Crawford counties. Maps of spray sites are available to view 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.


Spraying was completed as scheduled Friday, May 24 in Richland, Vernon and La Crosse counties. Spraying operations are finished for the year in Richland and Vernon counties.

Weather-permitting, Btk second-application sprayings are scheduled Tuesday, May 28 in Lafayette, Crawford, Grant, Iowa and La Crosse counties.



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. It will be loud.

During the spray season, the planes will apply one of two biological insecticides, depending on the site:

  • Foray 48B 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.
  • Gypchek consists of dead, crushed-up gypsy moth caterpillars infected with the nucleopolyhedrosis virus. The virus is specific to gypsy moth caterpillars only.

The spraying does not affect organic certification.

Both insecticides are not toxic to people, bees, animals, birds and plants.

People who are uncomfortable or have allergies may wish to stay indoors or leave the area until the 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.

Some sites will receive a second application of Btk and Gypchek about three to 10 days after the first application.

Feel free to share this information with others.


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 (

For more information or to view maps of the spray areas, please see the website You can also send an e-mail to


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