Can anyone identify the butterfly?

Hi PPM, I agree with Tex, looks like the Gulf Fritillary. This is a great shot of both, the butterfly and bougainvillea. Thanks.

Texasstar suggested Gulf Fritillary and that is at this site: http://www.butterfliesandmoths.org/species/Agraulis-vanillae The orange is deeper like the butterfly in the puzzle.
I don't think it is a sulphur because the orange is so deep in your picture and the wing is quite large. See: http://www.butterfliesandmoths.org/species/Phoebis-agarithe AND: http://www.butterfliesandmoths.org/species/Phoebis-philea AND: http://www.butterfliesandmoths.org/species/Abaeis-nicippe

Thanks, all. This gives me a starting point to work with.

Plumpy it is either a Blueberry Sulphur or a Orange Sulphur. I am making this based on you living in Southern CA.

It is hard to identify because we are only seeing one wing. I don't think it is a fritillary because those have spots on the wings, sort of like freckles. I think it could be a dryas julia: http://www.butterfliesandmoths.org/species/Dryas-iulia because the wing is more solid orange. it is in the same family as fritillaries.

I was going to say Gulf Fritillary. So we can assume it's some kind of Fritillary! Gorgeous bougainvillea, too. Thanks.

It looks a lot like a "Great Spangled Fritillary Butterfly", but not an expert, thanks for the post.