Taylor's Checkerspot Butterfly (Euphydryas editha taylori) is a medium-sized, colorfully checkered butterfly with a wingspan of less than 2.25 inches. It formerly occurred throughout the extensive grasslands, prairies, and oak woodlands of Vancouver Island, the Puget Sound basin, and the Willamette Valley. As this habitat has nearly disappeared, so has Taylor's checkerspot: only four populations remain today, and only one of them has over 50 individuals.

The checkerspot's decline is continuous and rapid. A site in Washington with almost 7,000 individuals was lost in 1997. It was extirpated from British Columbia in 2000. A single population remains in the Willamette Valley near Corvallis, OR. Three populations occur in the southern Puget Sound are on Fort Lewis and around the Bald Hills.

Taylor's checkerspot is primarily threatened by habitat loss and degradation. Grasslands covered hundreds of thousands of acres of the Puget Sound basin lowlands prior to European settlement. Today, less than 3% of that original landscape remains and much of it is degraded. The upland prairie in the Willamette Valley have been hit even harder. Only one-tenth of one percent of this important habitat remains. The vast majority of this grassland habitat was lost during the past 150 years because of agricultural and urban development, fire suppression and forest encroachment, livestock grazing, and invasion by native and non-native plants. In addition, pesticides and recreational activities pose a direct threat to the butterflies themselves.

On December 10, 2002 the Center for Biological Diversity, Xerces Society, Oregon Natural Resources Council, Friends of the San Juans, and the Northwest Ecosystem Alliance filed a petition with the U.S. Fish and Wildlife Service to protect Taylor's checkerspot under the Endangered Species Act. Listing under the ESA will require protection of specific grasslands, prairies, and woodlands as "critical habitat" for the checkerspot and the development of federal recovery plan. It will ensure that federal agencies act to save the checkerspot while encouraging state and private interests to participate as well.