Gypsy moths quiet in Northwest this year

Gypsy moth

Experts credit cool spring with keeping pest's numbers low


Capital Press

Gypsy moths cause millions of dollars of damage in Midwest and East Coast forests annually but hit a record low in Oregon and a 30-year low in Washington this past summer.

Just one gypsy moth was trapped in Oregon, near Beaverton. Elsewhere in the region, 13 were trapped in Washington and one in Idaho. None were found in Idaho in 2002, 2003 and 2006. And in 1975 and 1976 none were trapped in Washington, where trapping began in 1974.

Cool spring weather probably kept populations low this year, said entomologists in all three states.

The gypsy moth is one of America's worst forest pests. It attacks more than 500 species of deciduous and evergreen trees, has defoliated millions of U.S. trees and spreads quickly once established.

It has come to the Pacific Northwest annually since the 1970s, usually hitchhiking on recreational vehicles from the Midwest or East. Outbreaks have been eradicated and permanent populations have not been established.

Some 19,000 gypsy moths were trapped around Eugene in the mid-1980s but traps have only produced single and double digits in Oregon since then, said Barry Bai, entomologist with the Oregon Department of Agriculture. Oregon has been trapping since 1979, he said.

Seven of Washington's 13 moths this season were caught in Puyallup near South Hill Mall. Two were caught in Marysville and near Sunset Beach in Mason County. Single moths were caught in Renton and Fife, according to a Washington Department of Agriculture news release.

Washington's peak was 1,315 in 1983. Its previous low was 17 in 2002.

The department is inspecting catch sites for other evidence of gypsy moth activity before deciding whether to propose an eradication program for next spring. The last treatment was in Kent in 2007. A natural biological insecticide is sprayed, said John Lundberg, the department's pest program spokesman.

Gypsy moths could be "catastrophic" for the NW timber industry if it got established, Lundberg said.

Neal Kittelson, forest health data coordinator for the Idaho Department of Lands, said one moth was trapped in Idaho in 2010 and one in 2009. Larger numbers developed near Sandpoint in the late 1980s but were eradicated, he said.

Recommended for you