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US Fish & Wildlife Service FieldNotes

NEVADA FWO:  Highlighting the Mount Charleston Blue Butterfly



Region 8, July 26, 2011
Mt. Charleston blue butterfly.
Mt. Charleston blue butterfly. - Photo Credit: n/a

The Mount Charleston blue butterfly is a subspecies of the wider-ranging Shasta blue butterfly. It only occurs within the Spring Mountains of southern Nevada between 8,000 to 12,000 feet above sea level on Forest Service managed lands.  

The small adult Mt. Charleston blue butterflies emerge between July and September. They commonly feed on nectar from Clokey’s fleabane and Lemmon’s bitterweed, as well as other flowers. When adults are out feeding, males fly low to the ground looking for female mates.

Females lay eggs singly on their host plant, Torrey’s milkvetch. Larvae feed on the host plant and may be tended by ants. Ants tend and often protect blue butterflies for a nectar-like substance secreted by larvae called "honeydew." This substance is similar to the substance produced by aphids.

Although the adult Mt. Charleston blue butterfly may only live one or two weeks, it may require two years to complete its life cycle. It is suspected that it may take even longer if weather is unfavorable.

In March 2011, the U. S. Fish and Widlife Servcie (Service) determined the butterfly warranted protection under the Endangered Species Act (ESA), but that adding the subspecies to the Federal Lists of Endangered and Threatened Wildlife and Plants was precluded by the need to complete other listing actions of a higher priority. This placed the butterfly on the candidate list.

The Mt. Charleston blue butterfly is threatened by natural and human-caused habitat alterations, extreme weather events, and climate change. The Service is working with the Forest Service to ensure conservation measures will be implemented to protect the butterfly and its habitat.

Contact Info: Jeannie Stafford, 775-861-6300, jeannie_stafford@fws.gov