Courtesy Washington State Department of Agriculture
The Washington State Department of Agriculture said Tuesday that it plans to spray an insecticide over a total of 1,300 acres in two counties next spring to kill gypsy moth caterpillars.
The department will target 300 acres near Graham in Pierce County and 1,000 acres on and surrounding the U.S. Navy base in Kitsap County.
“I’m confident that our proposal will prevent gypsy moths from gaining a foothold in our state and protect our environment from this invasive threat,” WSDA pest program manager Jim Marra said in a written statement.
Washington, like other Western states, have been waging a 40-year war to keep out European and Asian gypsy moths. The pests feast on a wide-range of plants and are established in 20 states in the East and Midwest.
Massachusetts suffered its worse infestation in decades last year. Gypsy moths damaged 362,254 acres of state forests, according to officials. Gypsy moth eggs travel across the country attached to outdoor belongings.
WSDA this summer and fall trapped 117 gypsy moths, all of the European variety and the most since 1995.
The total doesn’t count about 100 female moths and 13 male moths collected by hand in early August from a bush in a Pierce County neighborhood. It was the first time WSDA has ever found female moths laying eggs. Female gypsy moths don’t fly and so aren’t lured into traps hanging from trees and fenceposts.
Most moths were trapped in Pierce or Kitsap counties, triggering the plan to spray Bacillus thuringiensis var. kurstaki, or Btk, in those places. The spraying will be in April or May, from the air and timed to when the caterpillars emerge. Btk is approved in organic farming, and it’s the chemical that WSDA has used in the past.
WSDA said it developed the spraying plan in consultation with the USDA and the University of Washington. The plan will go through public comment and environmental review before being made final.
WSDA also trapped gypsy moths in Clark, King, Island, Thurston and Whatcom counties, but not enough for the department to spray.
The 1,300-acre treatment will be one of the larger campaigns against gypsy moths WSDA has waged. But it will be much smaller than the last. In 2016, the department sprayed more than 10,000 acres in seven places. In the two years since, no gypsy moths have been detected in those areas, according to WSDA.