The Washington State Department of Agriculture’s annual gypsy moth summer trapping program is under way.

More than 22,000 small cardboard traps have been placed around the state — 875 in San Juan County — and are being checked every two to three weeks through September. Traps have been placed in all 39 counties.

Washington has never had a permanent population of the gypsy moth, the worst forest pest ever brought into the U.S. Nineteen states in the East and Midwest are not so fortunate; thousands of acres in those states are permanently infested.

The gypsy moth attacks more than 500 species of trees and plants. In its caterpillar form, the pest quickly strips trees and plants of leaves, destroying some and weakening others so they are susceptible to plant diseases. The caterpillar also destroys wildlife habitat, degrades water quality and triggers costly quarantines of timber, agriculture, and nursery products.

Washington’s last eradication treatment project took place in 2007 in Kent.

“We’ve kept this pest out of the state for 36 years,” said Jamie De Fore, trapping coordinator for San Juan County. “We want that record to continue.”

The number of gypsy moths caught annually in Washington varies widely. The largest number caught was 1,315 in 1983, and the smallest number in the last 30 years was 17 in 2002. Last year, 18 moths were caught.

For more information on Washington’s gypsy moth control program, call the gypsy moth hotline at 800-443-6684, or visit the agency’s website.