Papilio multicaudata, the two-tailed swallowtail, is a species of the family Papilionidae found in western North America from British Columbia to Central America. and a deeper yellow background color that can shade to orange. Females also have wider black stripes on the forewings than males. Males may engage in mud-puddling, and have claspers that can be seen as a yellow segment at the end of the abdomen, beyond the black abdominal stripes.
Host plants include: chokecherry, bitter cherry, Arizona rosewood, single-leaf ash, hoptree, and Arizona sycamore. In California it mostly uses California hoptree. Elsewhere in the West, it often uses green ash planted along city roads (in California, city habitats are usually occupied by western tiger swallowtails rather than two-tailed).
- P. m. grandiosus <small>Austin & Emmel, 1998</small> – Mexican mountains.
- P. m. multicaudata <small>Kirby, 1884</small> – widespread subspecies from southern Colorado, northern New Mexico, south through Arizona, New Mexico, Texas and much of Mexico.
- P. m. pusillus <small>Austin & Emmel, 1998</small> – widespread northern subspecies, in Rockies from southern Colorado north to Canada, throughout Washington and Oregon, and south along Pacific Coast at least to Ventura County, California, as well as in Sierras and Great Basin.