Food and Feeding: As do most butterflies, the swallowtail butterfly eats a great amount of food while it is a caterpillar. At this stage of its life, it will feed only on the foliage of umbellifers – a group of plants that includes carrot, fennel, and angelica – and it shows a marked preference for the leaves of milk parsley. The caterpillar has powerful jaws that are ideal for biting through tough plant material. It feeds nonstop and puts on weight quickly, outgrowing and molting (shedding) its skin four times before it changes to its adult form.

Once it becomes an adult, the butterfly no longer grows, so it only needs enough food to provide energy for flying and breeding. It gets its food in the form of sugary nectar, which it sucks from flowers using its long, tubular mouthpart called a proboscis. The proboscis is coiled up like a spring when it is not in use. The adult butterfly eats a wider range of food than the caterpillar. It will drink nectar from a broad range of flowers including milk parsley, ragged robin, and thistles. It is attracted both by the scent of the flower and by its color.

Breeding and Development: Young pupate (develop inside a cocoon) in fall and finally emerge as butterflies in the spring. Once the caterpillar is transformed into a butterfly, it begins to look immediately for a mate, since it has only a month to live. The male is attracted to a female by her scent, and they quickly pair. Spherical eggs are laid singly and attached to the leaflets of a food plant – usually milk parsley or fennel. After 8-10 days, young caterpillars emerge and start feeding.

The caterpillar’s sole activity is eating. It eats for 6-7 weeks before binding itself to a plant stem with the silk it produces. It then sheds its skin and spins a cocoon before beginning the final transformation into the adult butterfly. During this process, most of the bulk amassed by the feeding caterpillar is broken down to provide nutrients for a small core of cells that develop into the adult butterfly. When the butterfly is ready to emerge 2 weeks later, the pupa splits down the back and the butterfly is released. At first, its wings are crumpled and distorted, but as the wing veins are inflated by blood pressure, they expand and take shape. The swallowtail butterfly then flies off to look for a mate. The short lived adults make the most of the spring and summer mating season.

Defenses: The swallowtail is preyed on by spiders, birds, and small mammals at all stages of its life, but it is particularly vulnerable when it is a caterpillar or a pupa. Its main defense is disguise. When the caterpillar first hatches, it is black in color and has a white spot, which makes it resemble a bird dropping. But after its third molt, it emerges in a bright green skin flecked with orange and black spots, which makes it more conspicuous. At this stage, it protects itself by inflating a pair of orange horns from behind its head. The horns effectively ward off predators by producing a smell indicating that the caterpillar is foul tasting if eaten. Although harder to catch, the adult butterfly falls prey to birds.

Habitat: In most of Europe, the swallowtail butterfly is a familiar sight among flowery hillsides and meadows. Its broad, yellow and black wings carry it from flower to flower as it pauses to feed on nectar. Swallowtail butterflies found in countries off the European mainland, like those in England, are regarded as a separate species. They are smaller, darker, and weaker in flight. They also occupy a different habitat – mostly in marshes. It is thought that, while all swallowtail butterflies prefer dry, sunny climates, the species found in England lives in marshes because the availability of its food plant is greater there than in more arid regions.

Key Facts:
Characteristics:
Wings: 2 pairs, overlapping
Wingspan: 3-4 in.
Coloration: Yellow and black. Blue and red spots on hind wings

Breeding:
Breeding season: Spring-summer
Eggs: Spherical, laid singly
Egg to larva: 8-10 days
Larva to pupa: 6-7 weeks
Pupa to butterfly: 2-24 weeks, depending on time of pupation

Lifestyle:
Diet: Larvae feed on specific foliage. Adults drink nectar
Lifespan of adult: 3-4 weeks
Related Species: The closest relative is the Corsican swallowtail Papilio hospiton. Others include the scarce swallowtail Iphiclides podalirius and apollo  Parnassius Apollo, both common in Europe.
Distribution: Widespread throughout Europe and Asia to Japan. Also found in North Africa.
Conservation: Common and flourishing throughout most of its habitat.

Lifecycle of the Swallowtail Butterfly: 
1. Eggs are laid singly on a food plant. A dark spot indicates that a larva is developing.
2. Newly hatched, a caterpillar protects itself by mimicking bird droppings.
3. It then changes to a bright color, but deters predators by displaying two orange horns.
4. The caterpillar fixes itself to a stem and pupates, usually throughout the winter months.
5. Spring heralds the emergence of the adult. It breaks out of the pupa and within minutes has expanded its wings and is capable of flight.

Did You Know: Some swallowtail butterflies occasionally have black wings due to a condition called melanism.
The swallowtail butterfly normally lives in temperate climates, but one species is found in Alaska. This butterfly spends the long, cold winter in the pupal state, then emerges to produce a single brood during the short summer.
In 1975, an attempt was made to reintroduce the swallowtail to an area in England. Although 3,500 milk parsley plants were planted, the attempt failed.

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