A common and striking yellow and black butterfly seen across the eastern United States, this is the eastern tiger swallowtail, Papilio glaucus. It’s a male, because its hindwings have almost no blue — in females, there are big blue patches right above the black parts on the hindwings.
Females are actually dimorphic, and have two color options: the bright yellow, as above, or a darker brown/black, with no stripes. This color morph is thought to mimic the un-tasty pipevine swallowtail. Both versions have the blue on the hindwings.
Apparently there’s a matching western tiger swallowtail, Papilio rutulus, which lives in the western US (there’s an imaginary line roughly at the Rocky Mountains that demarcates the two species). The eastern tiger swallowtail is about two inches larger (nearly six inches across the wings!) than its western counterpart, and the western tiger swallowtail is missing the orange/yellow markings you can see on the outside edges of the “tails” of the butterfly above.
Eastern tiger swallowtails will drink nectar from just about anything, making them unusually unspecialized feeders in the butterfly world. Males exhibit a neat behavior called puddling, wherein they congregate on damp gravel, mud, or puddles and gather minerals which aid in reproduction.
Full disclosure: This photo was taken by my husband, the Cute Man. Thank you, Cute Man!