The Washington State Department of Agriculture (WSDA) is proposing to treat several areas in the Puget Sound region and Clark County next spring to eradicate multiple introductions of gypsy moth, a non-native, invasive pest that decimates trees. The proposal calls for treating a total of 10,500 acres of land at seven locations in Western Washington, the largest number of sites proposed for eradication of this voracious pest in more than a decade.
Next steps for WSDA include preparing two environmental reviews, consulting with local, state and federal agencies, and public outreach that includes informational open houses in affected communities. Postcards will be mailed this week to residents in the areas where treatment is proposed notifying them of the plan. WSDA will also post regular updates at www.agr.wa.gov/gypsymoth including specific information on treatment areas and public comment opportunities.
This past summer, WSDA trapped 32 European gypsy moths, the most caught since 2007. Traps also captured a record-breaking 10 Asian gypsy moths. More destructive than its cousin, the Asian gypsy moth feeds on a wider variety of trees and the female can fly, so populations can spread more quickly. It is the largest detection of Asian gypsy moth in Washington ever and the first time Asian gypsy moth has been detected here since 1999.
European gypsy moths are now established in 20 states, destroying millions of acres of trees annually and causing a host of problems for residents. The Asian gypsy moth has been detected, but has not yet become established in the United States.
Gypsy moths have been detected in Washington every year since 1977, but no permanent populations of this destructive pest have been established here due to WSDA’s consistently quick and successful treatment programs along with annual trapping and surveillance to detect introductions of the pest.
The gypsy moth caterpillars feed on trees and bushes, killing these plants in neighborhoods, parks, and forests. The pest destroys wildlife habitat and, by damaging protective tree canopies, it can degrade water quality in streams. An infestation can also trigger costly quarantines for timber, Christmas trees and other forest and nursery products.
WSDA’s proposal involves aerial applications of an organic treatment Bacillus thuringiensis var. kurstaki, or Btk, which is approved for organic agriculture and has a proven safety record around people, plants, pets, fish, birds and bees. It has been used for decades as a safe and effective treatment for combatting gypsy moth. Applications would be timed to target gypsy moth caterpillars emerging in the spring as they begin to feed on Washington’s trees.
WSDA’s preliminary proposal is to treat areas in:
- Pierce County, where several Asian gypsy moths were captured.
- Thurston County, where two Asian gypsy moths were captured.
- King County in Kent, where two Asian gypsy moths were captured, and Seattle, where 22 European gypsy moths were captured.
- Clark County, where one Asian gypsy moth was captured.
WSDA is proposing to apply Btk aerially, the most effective way to treat these areas. WSDA is proposing to treat a total of about 10,500 acres to eradicate this pest. In comparison, many states on the East Coast where gypsy moth is established treat hundreds of thousands of acres each year in hopes of slowing the spread of the pest as eradication is no longer possible.
“I’m proud of the fact that the Department of Agriculture has been so effective at protecting Washington’s neighborhoods and forests from this destructive pest,” WSDA Director Derek Sandison said. “We have had a very successful detection and treatment program, and I’m confident that our proposal will prevent gypsy moth from gaining a foothold in our state.”
The agency’s proposal is based on recommendations from a technical working group of gypsy moth experts that included researchers with the U.S. Department of Agriculture, Natural Resources Canada, the University of California at Riverside and the University of Washington.
Before a proposed treatment can take place, state and federal law require WSDA to assess potential environmental impacts and make these assessments available for public comment. Drafts of these documents will be posted for public review at www.agr.wa.gov/gypsymoth and libraries in the affected communities before treatment plans are finalized.