Papilio aristodemus, the Schaus' swallowtail or island swallowtail, is a species of American butterfly in the family Papilionidae. It is found in southern Florida with subspecies in the Bahamas, Hispaniola, and Cuba. Historically it occurred in tropical hardwood hammock from South Miami to Lower Matecumbe Key, Florida. It is named in honor of William Schaus. Caterpillar host plants are in the family Rutaceae and include hoptree (Ptelea trifoliata), citrus species, sea torchwood (Amyris elemifera), and lime prickly-ash (Zanthoxylum fagara).