Invertebrates
Old World Swallowtail
Papilio machaon · also called common yellow swallowtail
Over a Norfolk fen in early summer, a swallowtail glides on yellow-and-black wings with red-and-blue eyespots, Britain’s largest native butterfly and one found in no other part of the country.
Overview
The Old World swallowtail, Papilio machaon, is a Least Concern butterfly found across Europe, Asia, and North Africa, with related forms in northern North America. Its bold colours, smelly caterpillar defence, and rare British form in the Norfolk Broads make it one of the most striking butterflies of the Northern Hemisphere.
A butterfly with a stinking horn
The swallowtail caterpillar’s forked orange organ looks like a snake’s tongue and smells strongly, a defence that surprises many would-be predators.
Status
Least Concern overall, though the British form is rare.
Old World Swallowtail: common questions
What does the swallowtail caterpillar do when threatened?
It pushes out a forked orange organ behind its head that gives off a strong smell.
Where does the British swallowtail live?
It lives only in the fens of the Norfolk Broads, where its caterpillars feed on milk-parsley.
What do swallowtail caterpillars eat?
They feed on plants of the carrot family such as fennel and milk-parsley.
Where is the Old World swallowtail found?
It lives in meadows, fens, and open country across Europe, Asia, and North Africa, with related forms in northern North America.