Glaucopsyche piasus piasus

Arrowhead Blue

There are eight named subspecies of the arrowhead blue, five of which are in southern California. The nominate subspecies now has a type locality of "Hwy. 70 at Soda Creek, E. Branch North Fork Feather River Canyon, Plumas County, California," as determined by John Emmel in the Systematics book, but its range extends into southern California (by my definition) into Kern County from the Greenhorns to Nine Mile Canyon. The photos below are from Sherman Pass Road. This butterfly was first collected by Lorquin during the gold rush and sent to Dr. Boisduval in Paris. It's one of many named in the latter's 1852 article on the exotic butterflies of California (excerpted below).

Arrowhead blues are lupine feeders and are single brooded, with an adult flight time that depends on elevation, but generally it's late March to June. Nominate piasus tends to be at higher elevations. As you go south and southwest from the Sierras to lower elevations, you find subspecies excubita and sagittigera, respectively*. Eggs are placed singly on the lupines - I find them on the flower buds. Larvae are ant attended, as shown below. They feed straight through to pupation and overwinter as a chrysalis.

* According to Ken Davenport's Emmel Update, subspecies excubita and sagittigera meet around Frazier Park (Kern Co.) and Lockwood Valley Road (Ventura Co.).

Arrowhead Blue - Glaucopsyche piasus piasus
Glaucopsyche piasus piasus, the arrowhead blue, was starting its flight at higher elevations along Sherman Pass on May 15, 2014. This one was at Alder Creek, 6800' elevation. At lower elevations, and on a different lupine host, the darker subspecies excubita was flying in early to mid-April.
Arrowhead Blue - Glaucopsyche piasus piasus
Moving from Alder Creek to the high meadows east of Sherman Pass, the first butterflies had already begun to emerge as the last of the snow melted. I found this perfect nominate Glaucopsyche piasus flying with two other species in the meadows: Polygonia gracilis zephyrus and Pyrgus ruralis ruralis. May 15, 2014.
Arrowhead Blue - Glaucopsyche piasus piasus
An ant-attended last-instar larva on host lupines from the Alder Creek area. This was June 28, 2017; this should pupate and then overwinter at the base of the plant in that form before emerging ca. next May. Thanks to John Emmel for confirming the identification.
Original description of the Arrowhead Blue - Glaucopsyche piasus piasus
Boisduval's 1852 description from the Annales de la Société entomologique de France.

©Dennis Walker