The callippe silverspot butterfly is a medium-sized butterfly with a wingspan of approximately 2.2 inches. The upper wings are brown with extensive black spots and lines. The undersides of the wings are brown, orange-brown and tan with black lines and distinctive black and bright silver spots. The inner areas of the wings and body are covered with dense hair. This species was listed as endangered on December 5, 1997.
Since 1988, callippe silverspot butterflies have been recorded at the following locations:
- San Bruno Mountain and Sign Hill - near South San Francisco in San Mateo County
- Sears Point, in Sonoma County
- In the hills between Vallejo and Cordelia, in Solano County
The historical range also included populations in San Francisco County, for example Twin Peaks, and Joaquin Miller Park in Alameda County, which are now extirpated. The callippe silverspot butterfly was thought to still occur in Alameda and Contra Costa counties until recent genetic studies determined that the butterflies there are the non-listed Comstock’s silverspot butterfly.
The butterfly continues to be threatened by:
- Habitat degradation and fragmentation
- Climate change
- Illegal collection
- Habitat modification by non-native invasive plant species exacerbated by atmospheric nitrogen deposition from vehicle exhaust
- Habitat modification by encroachment of native shrubs, succession to coastal scrub, exacerbated by fire suppression
- Small populations
- Inability to restore larval host plants if removed
- Trampling of larvae and host plants by hikers along trails
The callippe silverspot butterfly occurs in grasslands with California golden violet (Viola pedunculata), which is its sole larval host plant.
Land on which the natural dominant plant forms are grasses and forbs.
The land near a shore.
The upper wings are brown with extensive black spots and lines. The undersides of the wings are brown, orange-brown and tan with black lines and distinctive black and bright silver spots. The inner areas of the wings and body are covered with dense hair.
The callippe silverspot butterfly is a medium sized butterfly with a wingspan of approximately 2.2 inches.
After transforming into a butterfly, the adult males live an average of 4.9 days and adult females live an average of 7.3 days but can live up to 14 days.
Adult callippe silverspot butterflies congregate at hill tops to find mates, which is called hilltopping behavior. Adult females lay their eggs during the early summer on the ground under leaf litter near the base of the larval host plant. A single female silverspot butterfly may lay as many as 600 eggs.
Larvae hatch from the eggs in about a week. After hatching, larvae eat the lining of the eggshell, take shelter in ground litter, and then enter diapause, a period of reduced activity and development. Most callippe silverspot butterfly larvae remain in diapause from early summer until the following spring. After diapause, the larvae eat the foliage of their larval host plant and go through five metamorphoses before developing into a pupa. The pupal stage of the callippe silverspot butterfly lasts about two weeks. The average adult flight season is from mid-May to late July with a few adults observed in April and early August.
Callippe silverspot larvae feed exclusively on California golden violet. Currently, there is no known method for successfully propagating and outplanting its larval host plant in restoration projects. Preferred nectar sources for adult callippe silverspot butterflies include both native plants, like Alameda coyote thistle, coyote wildmint, California buckeye, and non-native plants, like blessed milk thistle. At the King/Swett Ranch in the Cordelia Hills, callippe silverspot butterflies were found to travel up to one mile to nectar from the native California buckeye. Having diverse nectar sources available ensures that nectar is available throughout the flight season, which is typically mid-May to late July, and which may be particularly important during years with early or late emergence.
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