after doing a short search it may be in the papilio family of butterflies. see this site for the spicebush butterfly caterpillar, papilio troilus which it resembles but? not quite. funny because i found a spicebush caterpillar last year ...
They are especially interesting to me because my family also went to Santiago de Compostela on a bvacation/b back in 1978, traveling the old Pilgrim Road by car from Paris, with lengthy detours to take in sections of the other branches ... Yesterday afternoon around 5:30, a very tattered giant swallowtail (bPapilio/b cresphontes) appeared on the butterfly bush in my front garden. This was a new record for the mountain. I signalled my mother on the intercom and she came down ...