The Wisconsin Department of Agriculture, Trade and Consumer Protection says spraying is scheduled in Grant, Crawford, Iowa, Richland and La Crosse counties Wednesday through Friday.
Maps of spray sites are available at http://gypsymoth.wi.gov. Information is also available at 1-800-642-6684.
Spraying can start as early as sunrise and state officials warn the single-engine applicator planes are loud. The spraying is done to kill the caterpillars, which are invasive pests and can feed on the leaves of many species of trees and shrubs.