This photo is from Bodega Head earlier in September, but the flight season of American Ladies (Vanessa virginiensis) can be year-round in California.
In the photo above, look for the orange patch with a small white dot in the center (one on each forewing). This character is helpful when identifying American Ladies.
It's even easier when you can see the two large eyespots on the underside of the hindwing (see next photo). The other ladies in this area have four eyespots instead of two.
American Lady caterpillars feed on everlastings (Gnaphalium, most local species are now in the genus Pseudognaphalium) and Pearly Everlasting (Anaphalis).
P.S. Did you notice that it looks like this butterfly has 2 pairs of legs? Most insects have 3 pairs. The other pair is actually present in this butterfly, but the legs are much reduced — you can see the first pair of legs held close to the butterfly's body just below the eyes (they're very fuzzy).
Because these shorter legs are sometimes brush-like, butterflies in this family are called brush-footed butterflies (it includes groups such as the admirals, anglewings, checkerspots, crescents, fritillaries, and monarchs).