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Gypsy Moth spraying planned for campus and Arboretum

May 19, 2008

Aerial spraying to protect trees and forests from the potentially defoliating effects of the invasive gypsy moth could begin in Wisconsin within the next two weeks.

Trained pilots will treat approximately 233 acres on UW–Madison property as part of the 2008 gypsy moth suppression program, which is coordinated by specialists at the Wisconsin Department of Natural Resources (DNR). Treatment occurs at the request of local officials where spraying will take place.

University areas being treated this year include Picnic Point (54 acres), the Arboretum (54 acres), and 134 acres of the main campus.

The treatment to be used on campus is a biological insecticide using the active ingredient Bacillus thuringiensis var. kurstaki or Btk, a naturally-occurring soil bacteria that, when eaten by gypsy moth caterpillars, causes them to stop feeding and die. Btk is generally not harmful to people, pets or other wild animals and the formulation used this year has been listed among insecticides acceptable for use in organic production by the Organic Materials Review Institute. Some people may wish to remain indoors or avoid areas to be sprayed on the day that spraying occurs.

The start of the spraying program is weather dependent.

“It boils down to the weather,” said Andrea Diss-Torrance, gypsy moth program coordinator with the DNR. “The gypsy moth caterpillars must be of a certain size and the foliage needs to be developed enough to ‘catch’ the spray.”

Weather conditions also dictate when planes can get in the air, Diss-Torrance added. “If it’s too windy, we won’t spray. If it’s raining, we won’t spray. We weigh all these factors and pick the days when it all comes together,” she says.

Spraying typically begins early in the morning, perhaps as early as 5 a.m., when weather conditions are generally most favorable, but it can happen at any time of the day if the wind is light and there’s no rain in the immediate forecast.

Because of the flexible timing of the spraying schedule, DNR offers two different ways for local residents in treatment areas to keep abreast of plans. A toll-free information line is updated daily during the spraying season, or residents may subscribe to receive e-mail notification of spraying activities.

The toll-free information number is 1-800-642-MOTH (6684). Menu option #1 will list updated spray plans daily, starting in mid-May. To subscribe for e-mail notification, visit and look for the link to sign up in the “Who to Contact” box in the middle of the page. On the page you are directed to, scroll down to the bottom and fill out the fields under “sign up to receive email notification” and submit. Maps of all spray areas are also available at that Web site. For campus spray blocks, click on Dane County and the links to the PDF documents called “Madison 7, 19, 20 & 23” and “Madison 6, 8, 21, & 22.”

For more information about gypsy moths or the planned areal spray, visit: email, or call the Gypsy Moth Information Line at 800-642-6684.