Life History:

The Spring Mountains acastus checkerspot butterfly (Chlosyne acastus robusta) is a subspecies of the sagebrush checkerspot butterfly (Chlosyne acastus) belonging to the Nymphalidae family (brush-footed butterflies). The subspecies is only known to occur in the Spring Mountains in Clark and Nye counties, Nevada at elevations from approximately 5,900 to 8,900 feet above sea level. The majority of observations and habitat of the butterfly are within the boundaries of the Spring Mountains National Recreation Area managed by the U.S. Forest Service.

The butterfly has been observed in 17 areas. Four of these areas (1-Trough Spring, 2-Kyle Canyon, 3-Griffith Peak Trail/Harris Spring Road/Harris Mountain Road, and 4-Potosi Mountain/Mt. Potosi/Boy Scout Camp) are currently the only locations where known colonies occur. A colony is “a local, isolated population.” The remaining 13 areas are referred to as incidental observations or sighting areas, where intermittent observations of a few butterflies were recorded at a location. Spring Mountains acastus checkerspot butterflies observed in a colony or sighting area represent the overall known population of the subspecies.

Distribution and Habitat:

The subspecies is only known to occur in the Spring Mountains in Clark and Nye counties, Nevada at elevations from approximately 5,900 to 8,900 feet above sea level.

Threats:

The available information indicates fuels reduction projects (prescribed burning and/or clearing of underbrush) may have a negative impact on Spring Mountains acastus checkerspot individuals and habitat. The possible declining trends at the Potosi Mountain/Mt. Potosi/Boy Scout Camp colony site indicate that fuels reduction projects may be a threat to the Spring Mountains acastus checkerspot at this site. Also, potential declining population trends at the Griffith Peak Trail/Harris Spring Road/Harris Mountain Road colony site and the Trough Spring colony site indicate that vehicle and hiking traffic disturbing the butterfly flight period may be a threat to the subspecies. Additionally, drought may be an added stressor to the Spring Mountains acastus checkerspot butterfly at some locations where additional threats occur.

Actions / Current Information: