The U.S. Fish and Wildlife Service said Friday that it has found the mardon skipper in far more places than were known when the butterfly was first considered for protection.
Regional Director Robyn Thorson says extensive surveys have turned up 165 places where the butterfly can be found, compared to just 14 in 1999.
The mardon skipper is tawny orange, with a stout, hairy body less than an inch long. The caterpillars feed on grasses.
It is found in the southern Puget Sound and southern Cascades of Washington, and the Cascades and Coast Range of Southern Oregon and Northern California.
Conservation groups petitioned for protection in 2002.