NCW — The U.S. Forest Service will spray a bio-control substance on Blewett Pass and around Lake Wenatchee to kill moths.

The Forest Service will apply the substance to kill tussock moth caterpillars the second week of June and the last week of June, depending upon when the insects hatch, according to an Okanogan-Wenatchee National Forest news release.

Forest Service personnel are concerned there will be an outbreak of tussock moths this year, according to the news release.

The focus of the application will be in recreational areas. Tussock moths are a natural part of the ecosystem in Washington, but they can cause allergic reactions in people and pets, according to the news release.

Large outbreaks can also cause defoliation of trees, according to the news release. The last, large outbreak occurred from 1999 to 2002 and defoliated 45,000 acres of forest. But prescribed fires and forest thinning can improve forest health, resilience to insect outbreaks and decrease defoliation.

The bio-control substance the Forest Service will spray carries a naturally occurring virus that is only toxic to tussock moths, the news release states. The substance will be dropped by helicopters and people will want to avoid the areas during the days when it is dropped. The substance contains molasses and is sticky.

Tony Buhr: 664-7123 buhr@wenatcheeworld.com or on Twitter @TonyBuhr

Environment, county and health reporter

Tony Buhr has been a professional reporter for almost seven years. He worked for the Walla Walla Union-Bulletin as a cops and courts reporter. The Ellensburg Daily Records as a cops and courts, breaking news, agriculture and water reporter.