 Gypsy moth aerial spraying to start soon
MADISON -- With the emergence of leaves comes the hatching of gypsy moth caterpillars, a destructive pest that feeds on the leaves of many species of trees and shrubs in Wisconsin.
To combat the caterpillars, aerial spraying will begin in May in several counties under two state programs. Spraying typically begins in southern Wisconsin in mid-May and ends in northern Wisconsin in mid-June.
The Wisconsin Department of Agriculture, Trade and Consumer Protection operates a Slow the Spread Program (STS) and the Department of Natural Resources operates a Suppression Spray Program.
“The STS program generally sprays in the western part of the state where gypsy moth populations are low and emerging,” said Chris Lettau, STS program coordinator. “The objective of the program is to slow the spread of the gypsy moth westward. Spraying usually takes place in rural, forested areas.”
“The DNR Suppression Program serves the eastern part of the state where counties are quarantined for gypsy moth. In these areas of the state, gypsy moth populations are well established and areas are treated to prevent damage from very high populations of the pest.” said Andrea Diss-Torrance, suppression program coordinator. “This is a voluntary program that works with landowners and municipalities in spraying to manage this invasive pest.”
Under the STS program, the following counties and sites are scheduled to be sprayed: Bayfield, Chippewa, Clark, Crawford, Dunn, Eau Claire, Grant, Green, Iowa, Jackson, La Crosse, Monroe, Rusk, Trempealeau, Vernon and Washburn.
Under the suppression program, sites in the following counties are scheduled to be sprayed: Adams, Brown, Columbia, Dane, Fond du Lac, Green Lake, Jefferson, Kenosha, Marathon, Marquette, Menominee, Milwaukee, Outagamie, Racine, Rock, Shawano, Walworth, Washington, Waushara, and Winnebago. Spraying is also planned within the Dells of Wisconsin State Natural Area and in portions of the following state parks: Big Foot Beach, Devil’s Lake, Governor Thompson, Lake Kegonsa, Mirror Lake, Roche-A-Cri, and Rocky Arbor.
People can view maps of the specific areas scheduled for treatment on the state gypsy moth control program Web site. People who do not have access to the internet, can request to have spray maps mailed to them by calling 1-800-642-6684.
Residents living in or near spray sites can expect to see and hear low-flying planes beginning at around 5 a.m., weather permitting. Spraying is weather dependent and could be done on weekends as well as during the week.
“Spraying starts early in the morning because the humidity is higher and the winds calmer. These conditions allow for the best application of the product on the leaves,” Lettau said.
Planes will work in the area until the completion of the day’s spray plans and as weather conditions allow, into the late morning or afternoon.
Most sites will be sprayed with “Foray,” containing Bacillus thuringiensis var. kurstaki, or Btk, which is a naturally-occurring soil bacteria that kills gypsy moth caterpillars when they ingest it. One formulation of this bacterial insecticide used by the state’s cooperative gypsy moth program has been listed with the Organic Materials Review Institute as acceptable for use in organic food production. Five sites in Sauk, Waushara, and Menominee Counties will be treated with a gypsy moth-specific viral insecticide to prevent injury to a rare butterfly or moth species.
“Btk is not known to be harmful to people, pets or other wild animals,” Diss-Torrance said. “To avoid direct exposure to the spray, some people with severe allergies may wish to stay indoors or avoid areas to be sprayed on the day that spraying occurs.”
Suppression program sites receive one application of Btk. On average, this reduces the gypsy moth population on treated sites by 90 to 95 percent and prevents damage to trees due to severe defoliation. Some suppression sites will receive two applications of Btk to assure that late-hatching caterpillars are killed and westward spread is slowed. The second application will be applied seven to 10 days after the first application, depending on weather conditions.
The STS program will also use a mating disrupter from late June to the end of July. This pheromone interferes with the ability of male moths to find female moths in low, isolated populations. The suppression program does not conduct mating disruption treatments, because the populations it treats are much too high for this technique to have an effect.
More information about gypsy moths, the control programs and maps of the spray sites are available on the state gypsy moth Web site. Or, call the toll-free gypsy moth hotline at 1-800-642-MOTH (1-800-642-6684) to hear a recording of the programs’ most up-to-date spray plans or talk to staff.
FOR MORE INFORMATION CONTACT:
- Nkauj (pronounced ‘gow’) Vang, DATCP - (608) 224-4591, or Andrea Diss-Torrance, DNR - (608) 264-9247
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