This is the first post from Southern California, where the butterfly has been an uncommon vistor, but may now be establishing itself at Rancho Santa Ana Botanic Garden, where there is a wealth of host plant.

Thanks to Chris Barnhill for alerting me to the presence of this attractive butterfly. Even larger thanks to Hartmut Wisch, who lead me right to this attractive and cooperative specimen. I plan to return for a reshoot, to capture the colorful underwing.

Following my visit, Hartmut provided this info in an email:

"[At RSABG]They noticed this butterfly last year for the first time, though many more this year. I think it represents a small disjunct population established thanks to the happy coincidence of pioneers finding the right plant. Most of the reported strays never reproduce because they don't find their larval host. Looking at both your images, as well as Nancy Hamlett's, I'm convinced that these are Arizona Pipevine (Battus philenor philenor).

"The plant, just for reference, is Aristolochia californica. Though not native to SoCal, those at RSABG go >30 years back, so very well established. Re. flowering time, this year all seems a bit late. Some years they've been in flower by mid-March."