''Papilio elwesi'' is a

butterfly Butterflies are insects in the macrolepidopteran clade Rhopalocera from the order Lepidoptera, which also includes moths. Adult butterflies have large, often brightly coloured wings, and conspicuous, fluttering flight. The group comprises ...

of the family

Papilionidae Swallowtail butterflies are large, colorful butterflies in the family Papilionidae, and include over 550 species. Though the majority are tropical, members of the family inhabit every continent except Antarctica. The family includes the larges ...

. The species is endemic to China and

Vietnam Vietnam or Viet Nam ( vi, Việt Nam, ), officially the Socialist Republic of Vietnam,., group="n" is a country in Southeast Asia, at the eastern edge of mainland Southeast Asia, with an area of and population of 96 million, making it ...

. ''Papilio elwesi'' (along with '' P. maraho'') differs from all other '' Papilio'' species in the tail of the hindwing being so dilated that two veins are necessary to support it. Together these two species form the subgenus ''Agehana''. The larvae feed on

Lauraceae Lauraceae, or the laurels, is a plant family that includes the true laurel and its closest relatives. This family comprises about 2850 known species in about 45 genera worldwide (Christenhusz & Byng 2016 ). They are dicotyledons, and occur m ...

species.

Etymology

It is named for British botanist, entomologist, author, lepidopterist, collector and traveller,

Henry John Elwes Henry John Elwes, Royal Society, FRS (16 May 1846 – 26 November 1922) was a British botanist, entomologist, author, Lepidoptera, lepidopterist, Collecting, collector and traveller who became renowned for collecting specimens of lilies during ...

. elwesi Butterflies of Indochina Butterflies described in 1889 {{Papilionidae-stub