The Washington State Department of Agriculture (WSDA) has completed its annual trapping for gypsy moths, finding 42 of the plant-eating invasive pests in six counties, compared to 27 trapped last year.

Starting in June, WSDA employees placed 16,000 small, A-frame cardboard traps to catch male moths attracted to the traps because of a female-scent lure inside. The moths were captured in Clark County (3), Jefferson County (1), King County (26), Kitsap County (1), Pierce County (5) and Thurston County (6).

The last of the green colored traps were taken down this week.

Ten of the moths were Asian gypsy moth, not detected in this state since 1999. Although both European and the Asian species are damaging to forests and the overall environment, the Asian gypsy moth eats foliage from both deciduous and evergreen trees and shrubs. Also, the female Asian gypsy moth can fly, unlike her European counterpart, meaning Asian gypsy moth populations can spread much more quickly over a larger area.

Over the years, Washington has had more Asian gypsy moth introductions than any state in the U.S., arriving from egg masses attached to ships carrying cargo from Asian ports. Oregon recently reported two Asian gypsy moths trapped in Portland.

State entomologists will review trapping results and consult with U.S. Department of Agriculture and entomologists from other states before developing a proposed response. Any such proposal will need to 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 forest trees, fruit trees and ornamental trees in parks and neighborhoods.

Economic losses from gypsy moth infestations in the Eastern U.S. are estimated at $30 million annually and include losses from quarantines imposed on timber and agricultural products, including Christmas trees. It also can impact tourism.

Gypsy moth has been detected in Washington every year since 1977, but permanent populations have been stopped through consistent trapping efforts and eradication treatments when necessary. WSDA’s most recent treatment for gypsy moth took place last May near Yacolt, about 20 miles northeast of Vancouver. The aerial operation covered 220 acres, using an organic insecticide.