Danaus gilippus thersippus
Queens are overshadowed by and often misidentified as Monarchs, their more common and famous relative. But a fresh Queen is just as beautiful, the rich golden-brown ground color of the wings rimmed in black with a sprinking of white dots. They can appear pretty much anywhere in southern California, and I've seen them at the beach and - rarely - in my suburban garden. But I see them far more often in the deserts or in large open spaces where wild, native milkweeds may be growing. You may get lucky and come upon hundreds of them nectaring if you happen upon the right place at the right time.
For host plants, Queens are known to use Asclepias erosa, A. subulata and A. albicans, as well as Climbing Milkweed, Funastrum cynanchoides var. hartwegii and Hairy Milkweed, Funastrum hirtellum. I may try subulata in the garden and raise these. Queen larvae differ from Monarchs in that they have three pairs of filaments, not two.