Summer trapping nets 27 gypsy moths in Washington

OLYMPIA – The gypsy moth—a destructive forest pest that causes millions of dollars of damage each year in the U.S.—showed up again in Washington this past summer. The Washington State Department of Agriculture (WSDA) caught 27 gypsy moths in five counties, equaling the number detected in 2012 but far more than the single catch found in 2013.

Trappers found 16 moths in Yacolt, about 20 miles northeast of Vancouver; six moths in Seattle’s Capitol Hill neighborhood and single moths at two parks in Seattle; and at Neah Bay, Port Townsend and Lake Whatcom.

WSDA employees placed about 20,000 small, tent-shaped traps in trees, shrubs and other foliage in June and monitored them through the summer. By early October, the traps were taken down.

DNA analysis confirms that all moths caught were European gypsy moth and not the higher risk Asian gypsy moth. Asian gypsy moth females can fly up to 12 miles, making moth sites harder to detect. Female European gypsy moths are flightless.

Employees are now conducting physical inspections at the two multiple-catch sites, looking for additional evidence of gypsy moth activity—such as egg masses, pupal cases and cast skins. State entomologists will review the results and consult with U.S. Department of Agriculture and entomologists from other states before making a decision on how to respond. That determination will likely be made by the end of the year.

Gypsy moths typically arrive in Washington in the form of egg masses attached to outdoor articles, such as birdhouses and patio furniture, or hitchhike on vehicles arriving from the 19 permanently infested states on the East Coast and upper Midwest. The damage to foliage is done when gypsy moth caterpillars hatch in large numbers in the spring and devour the leaves of deciduous trees, many urban ornamental trees and fruit trees.

Permanent populations of the gypsy moth have never been detected in Washington. WSDA’s most recent treatment for gypsy moth was in Tukwila in 2013.