Wisconsin Department of Agriculture, Trade and Consumer Protection

serving the state of wisconsin since 1839

DATCP works to assure safe food, healthy people, animals, plants and environment, vibrant agriculture and fair business practices.

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Gypsy Moth

Aerial Spraying by the WI Gypsy Moth Slow the Spread Program 

The Gypsy Moth Slow the Spread Program (STS) run by the Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) annually conducts aerial spraying on gypsy moth caterpillar populations in mainly western Wisconsin and in isolated “hot spots” in the far-western part of the state. Its objective is to slow the spread and establishment of gypsy moth in western Wisconsin, the non-quarantined areas of the state.

Another program coordinated by the Department of Natural Resources (DNR) called the Gypsy Moth Suppression Program is a voluntary and separate spray program for landowners and communities located in the central and eastern parts of Wisconsin, which is quarantined for gypsy moth. Its objectives are to suppress gypsy moth populations and reduce defoliation to biologically acceptable levels.

You will need a PDF reader to view the following documents.

  • Maps of 2012 spray areas - Coming soon!
  • 2012 Spray Schedule - Available in May
  • 2011 Program Summary - A summary of last year's program.

Interactive Map

An interactive map to view 2012 spray sites will be available soon.

How Will I Know When Spraying Begins?

The start of spraying depends on the development of the gypsy moth, and it usually starts in May, right after the egg masses hatch. Before any spraying is done, we notify the local media, any nearby airports, local schools, health departments, and local and county law enforcement about our plans. We also send informational postcards to residents living in or near a spray area in April and May.

People can call the toll-free gypsy moth informational hotline at 1-800-642-6684 to listen to a recorded message about our daily spray plans and updates. 

How to Receive E-mail Notification of Spraying Activities and Updates

We send e-mail notifications as often as necessary during the spraying season to those who wish to receive it. The e-mails contain current spraying progress, upcoming spray plans and other updates. If people would like to be on our spraying notification list, please e-mail your name and county of residence to gypsymoth@wisconsin.gov

Insecticides Used

There are three different products, used separately, depending on the location of the spray area:

Spray Operations

We use the latest technology and science to keep the gypsy moth caterpillar from spreading to new areas or causing widespread defoliation in Wisconsin. Spray areas are precisely plotted using GPS technology, and the spray planes are outfitted with GPS equipment to accurately target the spray areas. This helps ensure that spray materials are deposited in the intended areas.

To get the best results from the insecticides used in our program, the spray planes must fly low over the tree tops, spraying directly onto the foliage the small larvae are feeding on to ensure good application. These planes are small, a little larger than a Cessna, but because they are flying low, they are fairly loud.

We usually spray in the morning because we need the high humidity and low winds to assure the spray does not evaporate or blow away. Planes remain in the area as weather conditions allow for the completion of the day’s spray plan. Spraying depends on good weather, so plans can change at the last minute.

How Spray Areas Are Selected

Unlike the voluntary DNR Suppression Program, the STS Program does not accept spray requests from the public. Instead, the spray areas in the STS Program are determined by trapping and egg mass survey results that are examined each fall. Spray areas are chosen based on comparison with results from previous years and knowledge of the factors influencing the risk of establishment and spread. Not all populations can be treated; those that pose the greatest risk are prioritized for treatment.

The Airplanes

The DATCP and the DNR contract an aerial spraying company to conduct the sprays. Our applicator is a company with extensive experience nationwide and with an excellent safety record. We hire the contractor who meets the high standards we demand; we are not obligated to accept the lowest bid.