The Swallowtail Butterfly is our largest native butterfly. It is very rare in England where it can only be found in the wetlands of the Norfolk Broads. It is restricted to this area because ‘milk parsley’ grows there which is the main food source for the Swallowtail Butterfly. It can only be seen for around one month in late May.

The Swallowtail Butterfly can easily be recognised because of its large creamy yellow wings which have black stripes near the edges and black vein-like markings. Its hindwings have two large red dots which are known as ‘false red eyes’ and the hindwings also have two long black extensions which looks similar to the tail of a swallow and this is why it has the name ‘Swallowtail Butterfly’.

Female Swallowtail Butterflies lay their eggs on the upper leaves of the milk parsley plants and when a caterpillar first hatches out of an egg it looks quite small and dark. It soon changes to a light green colour with orange spots and black stripes on its back. It also has two horns situated behind its head which can produce a rotting fruit smell to fend of predators. After a month of hatching, the caterpillar forms a chrysalis by wrapping silk around itself and then transforms itself into a beautiful Swallowtail Butterfly.