Swallowtail Butterfly

Scientific Name: 

Papilio machaon


None in common usage. In France the butterfly is know as Le Grande Porte-Queue (which roughly translates as "The Great Tail-bearer").


A stunning butterfly, notable for the characteristic tail streamers on the hind-wing. Yellow and black markings with a network of black veins. Also on the hind-wing is a band of bluish scales and a reddish eye spot. The under-wing is largely yellow with black veins and the eye spot is slightly paler. The larvae are just as spectacular and colourful. Winter is passed as a pupa. This is one of our rarest and most spectacular butterflies. The British race britannicus is a specialist of wet fenland for the male genitalia are very sensitive to humidity and become hard and unable to function in drier climates and is currently restricted to the Norfolk Broads. Here the adults can be seen flying powerfully over open fen vegetation, stopping to feed on flowers such as thistles and Ragged-Robin. The butterfly probably declined within its range during the twentieth century but has benefited over the last few decades from conservation management aimed at increasing open fen vegetation. There are also scattered records of migrants of the continental race.

Confusion Species: 

Not easily confused with other species.


Male 76-83mm, female 86-93mm

Log Book Number: 



Linnaeus, 1758


About 2 weeks.


A large, strong-flying butterfly restricted to the Norfolk Broads, although migrants are occasionally seen elsewhere.


The British race britannicus breeds only in open fens and marshes that support vigorous growths of Milk-parsley. The butterfly prefers areas of mixed fen usually dominated by sedge, or sometimes reed, which are cut periodically and contain tall, prominent food plants. The occasional migrants of gorganus can be found in almost any habitat but are most frequently seen on grassland near the south coast of England.


The native British race feeds solely on Milk-parsley. Occasional migrants of the continental race gorganus use a variety of umbellifers such as Wild Carrot and Wild Angelica.


UK BAP status: Not listed Butterfly Conservation priority: medium European threat status: not threatened Protected in Great Britain for sale only

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P. machaon