More than 8,000 acres in Pierce and Thurston counties will be treated this spring with an organic pesticide meant to kill gypsy moths.
It will be the largest treatment for the non-native, invasive pest in more than a decade. Dates for the aerial spraying have yet to be set.
The state Department of Agriculture will send post cards this week to people living in the areas slated for treatment, according to a department spokesman.
The department plans to treat 10,500 acres at seven locations. Included in that total are 7,000 acres covering portions of the Port of Tacoma, Northeast Tacoma, Fife and Milton, as well as 640 acres in Lacey and 600 acres in Gig Harbor.
Informational open houses will be held in the communities for people to learn more. Dates for the meetings have not been set. .
The department also will conduct two environmental reviews and consult with local, state and federal agencies before spraying the areas.
The proposal is to spray from the air an organic treatment called bacillus thuringiensis var. kurstaki, or Btk. The treatment is approved for organic agriculture and has been proven safe around people, plants, pets, fish, birds and bees, according to the department.
Applications would be timed to target gypsy moth caterpillars emerging in the spring as they begin to feed on Washington’s trees.
Over the summer the department trapped 32 European gypsy moths, the most since 2007. Traps also captured 10 Asian gypsy moths — the largest detection of Asian gypsy moths in Washington and the first time the species has been detected in the region since 1999.
Both species are known to decimate trees. Asian gypsy moths feed on a wider variety of trees than gypsy moths and its populations spread more quickly.
Gypsy moths have been found in Washington every year since 1977, but no permanent populations have been established because of the Department of Agriculture’s regular treatment programs.
Gypsy moth caterpillars feed on trees and bushes, killing the plants. An infestation can trigger quarantines for timber, Christmas trees and other forest and nursery products.
The Agriculture Department will post updates on its website at agr.wa.gov/gypsymoth that will include information on treatment areas and public comment opportunities.
Maps posted on the website show which areas will receive treatment.