Old World swallowtail

Papilio machaon, the Old World swallowtail, belongs to Papilionidae. Regional subspecies names include hippocrates in the Japanese museum account and britannicus in Britain. [2][1][4]

Yellow wings carry dark veins and extensive black basal and marginal markings. Blue crescents line the hindwing margin, with a red spot near the inner corner and a tail extending from each hindwing. [1]

The National Museum of Natural Science describes a northern distribution spanning Europe, Mediterranean North Africa, Asia and North America, extending south to the Himalayan foothills and Taiwan. [1]

In Britain, the resident swallowtail inhabits reedbeds and marshes of the Norfolk Broads. Continental migrants occasionally reach downland in southern England. [5]

Clark’s 1932 Smithsonian treatment documents specimens from Alaska and the James Bay–Hudson Bay region. It records Drexler’s 1860 James Bay expedition and the later transfer of material through museum collections. [3]

The Japanese museum portrait describes a smaller spring form in May–June and a larger summer form in July–August. [1]

In Norfolk, adults generally fly from May to July. A second brood occasionally appears from late August into mid-September. [5]

The museum account lists Apiaceae hosts including fennel, wild carrot and Angelica. The British britannicus population uses milk-parsley; continental migrants in Britain can use wild carrot. [1][4][5]

In the Norfolk Broads, adults fly strongly over reedbeds and marshes and visit ragged-robin and thistles for nectar. Females select tall, vigorous milk-parsley plants for egg laying. [5]

A 2026 whole-genome comparison found the British britannicus lineage genetically distinct and isolated within its European sample. Continental gorganus and nominate machaon were not separable in the same way. [4]

Norfolk fenland provides the milk-parsley used by resident larvae. Cutting reed and sedge helps maintain open conditions for this food plant, supporting the habitat managed for the butterfly. [5]

Britannicus and hippocrates are regional subspecies names within Papilio machaon. Historical North American material appears in Clark’s 1932 study under its contemporary regional treatments. [1][4][3]

The British sample in the 2026 genomic study showed higher inbreeding than the continental samples, without a detected increase in deleterious-mutation burden. [4]

The Norfolk Wildlife Trust describes a twentieth-century decline associated with habitat loss. Fen management, including reed and sedge cutting, maintains the open wetland vegetation required by the resident population. [5]

The red inner-corner spot and blue hindwing crescents lie within the yellow-and-black pattern. The hindwing tails complete the outline. [1]

Bold dark veins and margins structure the yellow wing fields. Small blue and red accents remain distinct at the hindwing edge and inner corner. [1]

Protect hindwing tails and small pattern details from handling and abrasion. Keep the display enclosed and out of direct sunlight and damp conditions.

Which plant supports the British resident population? Milk-parsley is the principal larval host in the Norfolk Broads; continental migrants in Britain can use wild carrot. [5][4]

What did the genomic comparison find? Britannicus was distinct within the European sample and had higher inbreeding, while the measured deleterious-mutation burden was not elevated. [4]

The museum account describes wing markings and regional host records. Norfolk Wildlife Trust documents British habitats and management, Clark records historical North American specimens, and the 2026 study compares European genomes. [1][5][3][4]