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, a larva the second year, and is suspected of having additional diapause during unfavorable years. Adults live one season, typically a short span of time (< 1 or 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 one or more of its larval host plants which includes Torrey’s milkvetch (Astragalus calycosus var. calycosus), mountain oxytrope (Oxytropis oreophila var. oreophila), and broad-keeled milkvetch (Astragalus platytropis). Its primary nectar plants are Clokey's fleabane (Erigeron clokeyi), Lemmon bitterweed (Hymenoxys lemmonii), Cooper rubberweed (Hymenoxys cooperi), and sulphur-flower buckwheat (Eriogonum umbellatum var. versicolor), however it has 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