The state's never-ending battle against a tiny, wriggling forest-munching pest came to the Mayfield Lake area Thursday.
Workers for the Washington Department of Agriculture sprayed a 7.5-acre parcel northeast of Ike Kinswa State Park as part of an eradication campaign aimed at the European gypsy moth.
The outdoor exterminators will be back twice more over the next two or three weeks spraying a sticky, sweet-smelling biological insecticide on emerging spring leaves.
"The leaves are out, we have an early spring, we have plenty of leaves on which the pesticide can fall," said John Lundberg, a spokesman for the state.
The pesticide, Btk, is based on a naturally-occurring soil bacteria that is grown industrially. It breaks down quickly in the environment, and the caterpillars must eat it for it to be effective.
It's a familiar drill in Lewis County. A stubborn infestation by the moths in the Vader area required the state to spray two years in a row, from the ground in 2001 and by helicopter in 2002.
That infestation was deemed destroyed in the fall of 2002.
A year later, a new, completely independent infestation was found at the intersection of Flynn Road and Ciannigan Hill Road north of state Route 122 near the northern shore of Mayfield Lake.
After this spring's spraying is complete at that site, the state will spread many paper tents around the Mayfield Lake area this fall as part of its statewide survey for the moths.
Gypsy moths were brought to the Boston area in the 1800s as part of an experiment on silkworms. The moths escaped and now infest 18 states.
The moths often come into the western states on lawn furniture, vehicles or camping equipment.
State etymologists suspect that a few quarter-size gypsy moth egg masses hitchhiked across the country with a family that lived near the infestation site for a year. The family has since moved back to the Midwest.
Brian Mittge covers politics, the environment and Lewis County government for The Chronicle. He may be reached by e-mail at bmittge@chronline.com, or by telephoning 807-8237.
