Papilio xuthus, the Asian swallowtail, Chinese yellow swallowtail, Japanese Swallowtail, Korean Swallowtail or Xuthus swallowtail, is a yellow-colored, medium to large sized swallowtail butterfly found in northeast Asia, northern Myanmar, southern China, Taiwan, the Korean Peninsula, Japan (from Hokkaidō to the Yaeyama Islands), Siberia and the Hawaiian Islands. The butterfly has been observed thrice in New Zealand. Once in Dunedin in 1996 emerging from a chrysalis in a car yard specializing in Japanese used cars; it is thought the chrysalis arrived through one of the cars. and later in Auckland in 2011 and 2016. It was also recorded in the state of Arunachal Pradesh, India, in 2014.

It mates multiple times in its life, leading to an increased genetic diversity in its young. It is preyed upon by a host of organisms, including the tree cricket Oecanthus longicauda, ant Lasius niger, and wasps (Polistes and Trogus mactator). P. xuthus utilizes color vision and color constancy while foraging for plants of the family Rutaceae.

It is common and not threatened. Papilio xuthus is common in urban, suburban, woods and orange orchards. The flight period is from May to August.

Males use both physical and visual cues to attract mates during the breeding season. Females of the species regularly mate with multiple partners. After mating, females use habitat and food quality to determine where they will oviposit their eggs.

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