A rare Asian gypsy moth was trapped recently near Lake Martha in Snohomish County, only the second time in the past two decades that the more-dangerous kin to the European gypsy moth has been found in the state.
Even one Asian gypsy moth could be reason enough to spray pesticide over the area, though the state Department of Agriculture has not made a decision, department spokeswoman Karla Salp said Monday.
In all, the department trapped 52 gypsy moths in 10 counties, all west of the Cascades. Aside from the one in Snohomish County, the trapped gypsy moths were of the European strain.
The department trapped nine in a neighborhood north of Bremerton, eight near a boat launch on Orcas Island, seven near Ames Lake in Redmond and four along Lake Symington in Kitsap County.
The department is hunting for egg masses in those areas to confirm the pests are reproducing and to pinpoint the outbreak, Salp said. Egg masses are difficult to find.
The department has trapped at least one European gypsy moth ever year since 1977. The European strain got lose in 1869 in Medford, Mass., and is now established in 20 states. The pest defoliates 500,000 to 1 million acres of forest land a year, according to the USDA.
The Asian strain of gypsy moth has not gotten a foothold in the U.S., but is considered potentially more dangerous because it can spread faster. The females, as well as the males, fly. Female European gypsy moths are flightless.
In 2015, the agriculture department trapped 10 Asian gypsy moths at six locations. The following spring, the department responded by spraying a total of 10,500 acres. Asian gypsy moths have not been found in those areas since. The department had previously trapped an Asian gypsy moth in 1999.
The gypsy moth catch this year was modest compared to some previous years. The department trapped a gypsy moth in Bangor, the site of a Naval base on the Kitsap Peninsula, where the department sprayed last spring.
The department did not trap any gypsy moths in a Pierce County neighborhood where the department also sprayed.
The agriculture department will decide in December or January whether to spray any areas next spring when caterpillars emerge. The department typically contracts with an aviation company to spray Bacillus thuringiensis var. kurstaki, or Btk.
Gypsy moths spread by attaching eggs to belongings.