Nevada Fish & Wildlife Office
Pacific Southwest Region

Mt. Charleston blue butterfly

(Icaricia shasta charlestonensis)

Mt. Charleston blue butterfly
Class: Insecta
Order: Lepidoptera
Family: Lycaenidae
Genus: Icaricia
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
nectar plants: Torrey's milkvetch and Clokey fleabane
Habitat: relatively flat ridgelines above 8,202 ft, but isolated individuals have been observed as low as 6,562 ft of the Spring Mountains, located approximately 25 miles west of Las Vegas in Clark County, Nevada
 

Official Status:

Endangered, 9/18/13
 

Life History:

The Mt. Charleston blue butterfly is generally 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 for at least one season or possibly more. Adults live one season, typically a short span of time (2-4 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 Mt. Charleston blue butterfly is dependent on plants both during larval development (larval host plants) and the adult butterfly flight period (nectar plants). The Mt. Charleston blue butterfly requires areas that support Torrey’s milkvetch (Astragalus calycosus var. calycosus), the only known larval host plant for the subspecies. Torrey’s milkvetch and Clokey fleabane (Erigeron clokeyi) are the primary nectar plants for the subspecies; however, butterflies have also been observed nectaring on Lemmon’s bitterweed (Hymenoxys lemmonii) and Aster.

The wingspan of the Mt. 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 Mt. 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 Mt. 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:

 

loss of vegetative cover, extreme weather (drought, late season snowstorms, unusually wet weather, etc.)

 

Actions / Current Information:

 

09/18/2013
  • Final listing rule: Endangered and Threatened Wildlife and Plants; Determination of Endangered Species Status for Mount Charleston Blue Butterfly (.722MB PDF)
     
  • News Release: Service Protects the Mount Charleston Blue Butterfly under the Endangered Species Act
     
  • Q&A:
    Proposed listing of the Mt. 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 Mt. 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 Mt. 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 Mt. Charleston Blue Butterfly as Endangered or Threatened
     
  • News Release: Protection of the Mt. Charleston Blue Butterfly under Endangered Species Act Is Warranted but Precluded
     
  • Q&A: Mt. Charleston Blue Butterfly 12-Month Finding
     
     
    05/30/2007
  • Fish and Wildlife Service to Initiate Status Review of Mt. Charleston Blue Butterfly
     
  • Q&A: Mt. Charleston Blue Butterfly 90-Day Finding
     
  • Federal Register: Notice-Endangered and Threatened Wildlife and Plants; 90-Day Finding on a Petition To List the Mt. Charleston Blue Butterfly as Threatened or Endangered

     
     
    10/20/2005
  • Petition
     
     
     
     
     
     
     
    Last updated: April 16, 2014