Nevada Fish & Wildlife Office
Pacific Southwest Region

Mount Charleston blue butterfly

(Plebejus shasta charlestonensis)

Mt. Charleston blue butterfly
Class: Insecta
Order: Lepidoptera
Family: Lycaenidae
Genus: Plebejus
Species shasta
Sub-Species: charlestonensis
Length: wingspan ranges from ¾ to 1 inch
Lifespan: (see Life History section below)
Feed: larval host plant: Torrey Milkvetch, Kern plateau milkvetch, Broad keeled milkvetch
nectar plants: primarily Clokey's fleabane, Lemmon bitterweed, Cooper rubberweed, sulphur-flower buckwheat
Habitat: relatively flat and open areas with exposed soil and rock substrates with short, widely spaced forbs and grasses above 8,200 ft, but isolated individuals have been observed as low as 6,500 ft of the Spring Mountains, located approximately 25 miles west of Las Vegas in Clark County, Nevada
 

Official Status:

Endangered, 10/21/2013
 

Life History:

The Mount Charleston blue butterfly is presumed to diapause (period of suspended growth or development similar to hibernation) at the base of the larval host plant or in the surrounding substrate as an egg the first year and a larva the second year and suspected of having additional diapause during unfavorable years. Adults live one season, typically a short span of time (<1-2 weeks) during the known flight or breeding period. The typical flight and breeding period for the butterfly is early July to mid-August with a peak in late July, although the species has been observed as early as mid-June and as late as mid-September

Like most butterfly species, the Mount Charleston blue butterfly is dependent on plants both during larval development (larval host plants) and the adult butterfly flight period (nectar plants). The Mount Charleston blue butterfly requires areas that support Torrey’s milkvetch (Astragalus calycosus var. calycosus),Kern plateau milkvetch (Astragalus lentiginosus var. kernensis), and Broad keeled milkvetch(Astragalus platytropis) the only known larval host plant for the subspecies. Clokey's fleabane (Erigeron clokeyi), Lemmon bitterweed (Hymenoxys lemmonii), Cooper rubberweed (Hymenoxys cooperi), and Eriogonum umbellatum var. versicolor (sulphur-flower buckwheat) are the primary nectar plants for the subspecies; however, butterflies have also been observed to use other species for nectar.

The wingspan of the Mount Charleston blue butterfly ranges from ¾ to 1 inch. Males are dark to dull iridescent blue and females are brown with a blue overlay. Their underside is gray, with a pattern of black spots, brown blotches and pale wing veins to give it a mottled appearance.

More photos at: http://flickr.com/photos/usfws_pacificsw

 

Distribution and Habitat:

 

The Mount Charleston blue butterfly is a distinctive subspecies of the wider ranging Shasta blue butterfly (Icaricia shasta), a member of the Lycaenidae family (little butterfly family). The subspecies is known to occur only at high elevations of the Spring Mountains, located approximately 25 miles west of Las Vegas in Clark County, Nevada. The butterfly requires open habitat that supports its larval host plant, Torrey's milkvetch (Astragalus calycosus var. mancus), which grows between 5,000 to 10,800 feet on the east side of the Spring Mountains. The core colonies for the Mount Charleston blue butterfly are located on less than 9 acres in Kyle and Lee Canyons, on lands managed by the Forest Service in the Spring Mountains National Recreation Area of the Humboldt-Toiyabe National Forest.

 

Threats:

 

Threats and conservation issues to the Mount Charleston blue butterfly include: loss and degradation of habitat due to changes in natural fire regimes and succession; the implementation of recreational development projects and fuels reduction projects; and the increases in nonnative plants will increase the inherent risk of extinction of the remaining few occurrences of the Mount Charleston blue butterfly.  These threats are likely to be exacerbated by the impact of climate change, which is anticipated to increase drought and extreme precipitation events.

 

Actions / Current Information / References (as cited therein):

 

09/18/2013
  • Final listing rule: Endangered and Threatened Wildlife and Plants; Determination of Endangered Species Status for Mount Charleston Blue Butterfly (.456 MB PDF)
     
  • News Release: Service Protects the Mount Charleston Blue Butterfly under the Endangered Species Act
     
  • Q&A:
    Proposed listing of the Mount Charleston blue butterfly as endangered
    09/26/2012
  • Federal Register: Endangered and Threatened Wildlife and Plants; Proposed Listing of the Mount Charleston Blue Butterfly as Endangered and Proposed Listing of Five Blue Butterflies as Threatened Due to Similarity of Appearance
     
  • News Release: Service proposes to protect the Mount Charleston blue butterfly and five similar butterflies under the Endangered Species Act
    Agency seeks information from the public, scientific community before making final decision
     
  • Q&A:
    • Proposed listing of the Mount Charleston blue butterfly as endangered
    • Proposed listing of the Lupine blue butterfly, Reakirt’s blue butterfly, Spring Mountains icarioides blue butterfly, and two Spring Mountains dark blue butterflies as threatened
         
    03/07/2011
  • Federal Register: 12-Month Finding on a Petition to List the Mount Charleston Blue Butterfly as Endangered or Threatened
     
  • News Release: Protection of the Mount Charleston Blue Butterfly under Endangered Species Act Is Warranted but Precluded
     
  • Q&A: Mount Charleston Blue Butterfly 12-Month Finding
     
     
    05/30/2007
  • Fish and Wildlife Service to Initiate Status Review of Mount Charleston Blue Butterfly
     
  • Q&A: Mount Charleston Blue Butterfly 90-Day Finding
     
  • Federal Register: Notice-Endangered and Threatened Wildlife and Plants; 90-Day Finding on a Petition To List the Mount Charleston Blue Butterfly as Threatened or Endangered

     
     
    10/20/2005
  • Petition
     
     
     
     
     
     
     
    Last updated: January 28, 2014