Hemiargus ceraunus gyas
The Ceraunus Blue can be found much of the year, especially in the deserts where it uses Mesquite, Catclaw, and various rattlepods. It flies with - and closely resembles - Leptotes marina, but along the hindwing's upper edge, ceraunus has two dark spots that distinguish it from marina. Reakirt's Blue may also be flying with either or both of these two, and it shares the two hindwing dots with ceraunus, but it is easily recognized by the row of dark macules on the forewing. I put a side-by-side illustration below.
This is a species of blue that will open its wings occasionally for patient photographers, as will Reakirt's and the Marine Blue.
Larvae are extremely variable and can be difficult to distinguish from some other lycaenid species. I thought the one I found on Astragalus palmeri below could be a Gray Hairstreak. However, we know that ceraunus has a yellow form, and that it uses this species of Astragalus, and I've seen adults in the immediate vicinity in the past. One way to be sure is to take it home and rear it to adulthood, but I wasn't prepared to do that (and can live with the slight uncertainty).