Habitat
Meadows and flowery hillsides up to 2000m. In the UK the swallowtail is found in marshy fenland - the only habitat where its food plants still grow in abundance.
Geographical spread
Widespread throughout Europe, Asia and Japan. Also found in north Africa. Considered rare in UK. Locally found in East Anglia, and Wicken Fen, near Cambridge
Current population: not available
Status: pending info from BCG/ EN
Size: Wingspan between 75mm to 100mm
Average life expectancy
As a caterpillar 6-7 weeks. The pupa can develop into an adult butterfly in the same season, but often over-winters for up to six months (UK). The adult butterfly lives for only one month.
Normal diet
The caterpillar stage shows a preference for umbellifers - a group of plants including fennel, carrot and angelica. The Marsh Hog's Fennel, or Milk parsley, provides a staple diet and is common is marshy fenland. Adult butterflies will take nectar from a variety of plants in the habitat. They need energy only for flight and breeding.
Normal lifestyle
During the breeding season, in late spring, early summer, adult butterflies lay their eggs on the food plant, mainly Marsh Hog's Fennel (Peucedanum palustre).
The newly hatched caterpillars immediately consume the leaves of the plant and grow rapidly. They moult their skins several times, and change in appearance. Initially they appear to be a bird-dropping, a defensive camouflage, changing into the more familiar green, ringed with black and orange. If disturbed, the caterpillar has a further defence in the form of two orange processes behind the head that it can erect when alarmed.
After several weeks of feeding, the caterpillar pupates, attached to its host plant, often over winter.
The adults hatch, usually in May, and feed on nectar from flowers in their local habitat, attracted by scent and colour. The adults have tailed hind wings and bright markings. The species most closely resembling Papilio machaonin Europe is the Corsican Swallowtail Papilio hospiton. World-wide there are over 500 swallowtail butterfly species.
Previous geographical spread
This butterfly is common across Europe - the British race previously occupied wider areas of its current habitat.
Reasons for decline
Land drainage and reclamation for agriculture have reduced the areas of natural marsh in the UK. The dependence on its food plants, which only grow in these areas has led to declining populations. In the UK the swallowtail may only produce one brood, occasional two. In warmer climates there may be up to three broods.
Conservation projects
Awaiting info from BCG/ EN. Notably Wicken Fen, near Cambridge, has been the site of conservation. Current activities co-ordinated by the Butterfly Conservation Group and English Nature