I noticed many of this type of Butterfly sailing overhead on Mt. Diablo and wondered when one would land . My patience paid off when one finally landed within reach on poison oak . This one looks like it had a tough life judging by her tattered and torn wings , but she still flew gracefully . I think that it may be the California sister butterfly thanks to the post by Margarethe Brummerman in Arizona who had a similar butterfly called the Arizona sister whose open wing pattern looks identical ! She said the outside wing pattern is different though for the California species which is really interesting . Thanks for any comments , sincerely Beth