The Old World Swallowtail (Papilio machaon) is a butterfly of the family Papilionidae. The butterfly is also known as the common yellow swallowtail or simply the swallowtail (a common name applied to all members of the family). It is the type species of the genus Papilio and occurs throughout the Palearctic region in Europe and Asia; it also occurs across North America, and thus, is not restricted to the Old World, despite the common name. The imago typically has yellow wings with black vein markings, and a wingspan of 65–86 millimetres (2.6–3.4 in). The hind wings of both sexes have a pair of protruding tails which give the butterfly its common name from the resemblance to the birds of the same name. Just below each tail is a red eye spot. Papilio machaon was named by Carl Linnaeus in the 10th edition of Systema Naturae in 1758, alongside nearly 200 other species of butterfly. Later, Pierre André Latreille designated it as the type species of the genus Papilio.The specific epithet machaon refers to Machaon, son of Asclepius in the works of Homer. There are 37 recognized subspecies. Papilio machaon gorganus is strongly migratory in Europe and may be found in almost all habitats. In some countries, P. machaon and its subspecies are protected by law. Papilio machaon machaon is protected by law in six provinces of Austria, Czech Republic, Slovakia, Hungary, Romania, and Moldova. The species is protected in the United Kingdom, and subsp. verityi is protected in India.