Gypsy moth aerial spraying update

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(NEWS RELEASE) -- 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 2014 consists of treating 60 sites, involving approximately 186,220 acres in 18 counties, mostly in western Wisconsin.

WHEN: Friday, May 23, weather permitting.

WHERE: Select sites in Lafayette and La Crosse counties.

WHY: 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 2014 spray season kicked off Thursday, May 22 with aerial treatments at two small blocks in Green County.

TREATMENTS: Three different treatments will be done in select areas: two utilizing the biological insecticides Btk and Gypchek; as well as a synthetic female moth pheromone which serves as a mating disruptor.

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.

Planes will apply the pheromone flakes, depending on the site:

• Pheromone flakes are a mating disruption product. The flakes are tiny – about the size of a grain of rice. They are flat and green. The sticky flakes are applied at a rate of one to two flakes per square foot of tree canopy.

• The pheromone flakes do not kill or harm any gypsy moths. They are applied to trick adult male moths from finding females to prevent reproduction. In nature, male gypsy moths fly, while female moths cannot. In order to find each other and reproduce, females release a pheromone for the males to track and follow.

• Similarly, the flakes also release this pheromone. The male moths then track and follow a false trail and, finding no female, no reproduction occurs. The same pheromone also is used as a lure to catch male gypsy moths in traps. The pheromone is undetectable to other insects.

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.

Both insecticides and the mating disruptor are 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 and Gypchek about three to 10 days after the first application.

FOR MORE INFORMATION: 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 (

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