Moth count in progress

This gypsy moth caterpillar eats foliage and kills trees. - Contributed Photo
This gypsy moth caterpillar eats foliage and kills trees.
— image credit: Contributed Photo

Since mid-June, 81 gypsy moth traps have gone up and been monitored on Mercer Island, part of a 36-year-old Washington Department of Agriculture campaign to prevent infestations in the state of one of the most destructive invasive species that U.S. forests have ever known.

“Early detection is absolutely critical,” said Jim Marra, managing entomologist for the Agriculture Department. “Our role is pretty important in keeping them not just out of Washington, but out of the whole West Coast.”

Marra said there are two types of gypsy moths in the United States: Asian and European. European gypsy moths were introduced to the United States in 1869 by a French scientist trying to breed a new kind of silkworm. The Asian variety arrived in egg masses on ships coming across the Pacific Ocean, according to entomologists.

Gypsy moth caterpillars feed on foliage, killing trees.

Marra said moths arrive from infested areas as egg masses attached to cars, furniture or any other flat surface. Since the gypsy moth program began, the Department of Agriculture has caught 1,571 moths in King County and 67 on Mercer Island, according to data on its Web site.

Marra said that after the trapping season is over, the department reviews the data and decides whether and where to spray a gypsy moth pathogen known as BtK.

Spraying has been controversial in the past, though the department has not had to for the last three years.

For more information on gypsy moths, call the state’s hotline at 1-800-443-6684 or see the Agriculture Department’s gypsy moth Web site:

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