Glaucopsyche piasus umbrosa

Smoky Arrowhead Blue

Another subspecies named in the 1998 Systematics publication (pp.172-3). The types were collected by John Emmel in the mid-1980s on a slope two-tenths of a mile east of Big Laguna Lake in the Laguna Mountains. He found them associated with Lupinus formosus. What sets these apart from other arrowhead blues is the darker ventral ground color, with the white "arrowheads" less developed. They fly in a single brood in the spring, with most records from April to about mid-May. As with the others in this species, the eggs are placed in the lupine flower buds, larvae emerge and feed to pupation, and overwinter as chrysalises. Eggs are easily found as shown below.

Smoky Arrowhead Blue - Glaucopsyche piasus umbrosa
Glaucopsyche piasus umbrosa, the 'smoky' arrowhead blue, was flying off Old Highway 80 near Guatay in rural San Diego Country on May 11, 2013. Note the eggs!
Smoky Arrowhead Blue - Glaucopsyche piasus umbrosa
Another umbrosa above and below on the same day. The host is a lupine - Lupinus formosus.
Smoky Arrowhead Blue - Glaucopsyche piasus umbrosa
Special thanks to Andrew Kim for the location.
Photo of Lupinus formosus from the Guatay area
Lupinus formosus (western lupine) patches are where to look for this little blue butterfly.

©Dennis Walker