Speyeria nokomis carsonensis

Carson Valley Silverspot

Family: Nymphalidae · Class: Insecta · Order: Lepidoptera

Conservation status: G3T1T2 S1

The Carson Valley silverspot is a subspecies of the Nokomis fritillary, a large butterfly in the family Nymphalidae. Adults display the characteristic fritillary pattern with orange forewings marked by dark spots and lines. Males typically measure 55-70 mm (2.2-2.8 inches) in wingspan, while females are larger at 65-80 mm (2.6-3.1 inches). The hindwings feature silver spots on a dark background, giving the species its common name. Males exhibit bright orange coloration on the dorsal wing surfaces, while females are generally duller with more subdued orange tones and heavier black markings. The Carson Valley silverspot has an extremely restricted range, occurring only in Carson Valley of western Nevada and adjacent areas of eastern California along the Nevada border. This subspecies represents one of the most geographically limited populations of Speyeria nokomis. The species is found primarily in Douglas County, Nevada, with potential occurrence in adjacent Alpine County, California. The total range encompasses less than 50 square kilometers of suitable habitat. This subspecies inhabits wet meadows and riparian areas at elevations between 1,400-1,500 meters (4,600-4,900 feet). Adults require areas with permanent or semi-permanent moisture that support their host plants. The habitat consists of alkali meadows, wet pastures, and irrigated fields where native violets persist. These areas are typically associated with natural springs, seeps, or irrigation systems that maintain soil moisture throughout the growing season. Adult Carson Valley silverspots are active from late June through August, with peak flight occurring in July. Males patrol suitable habitat searching for females, often flying close to the ground among host plants. Females deposit eggs singly on or near violet plants, particularly species in the genus Viola. Larvae feed exclusively on violets and overwinter as first instars, resuming development the following spring. The species completes one generation per year, with adults living approximately 2-3 weeks during the flight period. Adults nectar on various wildflowers including thistles, mint species, and other composite flowers found in their wet meadow habitat. The Carson Valley silverspot holds a global rank of G3T1T2, indicating it is critically imperiled to imperiled as a subspecies, with an estimated 1,000 to 10,000 individuals remaining. In California, the subspecies receives a state rank of S1, reflecting its critically imperiled status with typically fewer than five occurrences. The primary threats include habitat loss from agricultural conversion, urban development, water diversions, and groundwater pumping that eliminates the wet meadow conditions essential for both adults and host plants. Livestock grazing and invasive plant species also degrade habitat quality. Climate change poses additional risks through altered precipitation patterns and increased drought frequency, which could further reduce the already limited suitable habitat. No formal recovery plan exists for this subspecies, though habitat protection and restoration efforts in Carson Valley could benefit the remaining populations.

Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, and more.