This dazzling bit of the New World Tropics was introduced into southern California in the 19th Century --we don't know how-- and was first recorded in the Bay Area before 1908, though it seems to have become established there only in the 1950s. It can be quite common in the East and South Bay --particularly in Berkeley-- and has been found breeding spontaneously as far inland as Fairfield where, however, it is not established. There are scattered records in the Central Valley and even up to Folsom, perhaps resulting from people breeding the species for amusement or to release at social occasions. According to Hal Michael, who grew up in South Sacramento, this species bred there in abundance on garden Passiflora in the early 1960s. It seems to have died out by the early 1970s, however. Intolerant of hard freezes, it still managed to survive the record cold snap of 1990 that largely exterminated the Buckeye regionally!
This butterfly has no native host plant in California and is entirely dependent on introduced species of the tropical genus Passiflora (Passion Flower, Passion Vine), including the common Maypop (P. incarnata) and P. X alatocaerulea. However, it will not eat all of the Passiflora in cultivation in California.
In the Bay Area this species can be seen flying any day of the year, if it is warm and sunny enough.