Swallowtail Butterflies

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Scientific name:  Papilio machaon

Size:  Wingspan approximately 90mm

Distribution:  Found in the Norfolk Broads.  Some migrants from the continent show up in other parts of England and Wales.

Months seen:  May to July

Life span:  Up to eight months

Habitat:  Wet fenland and marshes

Food:  Nectar. The caterpillars feed on milk parsley (Peucedanum palustre)

Special features:  It would be difficult to confuse Swallowtails with any other butterfly.  It's one of the prettiest and certainly the largest butterfly found in the UK.  The name comes from the two tail-like extensions on the hind wings.

The young caterpillars have the appearance of bird droppings to protect themselves from predators.  As they get larger they become pale green with black lateral stripes and orange spots.  They also have a strange appendage on top of their heads which looks like an orange coloured snakes forked tongue.  It's called an 'osmeterium', and for added effect it can be flicked in and out.  The caterpillar is also capable of emitting a powerful scent similar to rotting fruit.

Any Swallowtail butterflies spotted outside of the Norfolk Broads are more likely to be the continental subspecies Papilio machaon gorganus.  Continental Swallowtail butterflies frequently arrive in the UK and have shown up in many of parts of England.  Their markings are slightly paler in colour, but they are larger and stronger than the British subspecies britannicus.  They've been known to breed here, and the less fussy caterpillars are able to surive by feeding on plants such as hogweed, fennel and carrot.

Related Pages

• UK Safari Butterfly Section
• UK Safari Caterpillar Section
• Identify other wildlife
• What's Out Now?