The swallow tail butterfly is very easy to identify. It is the largest resident butterfly found in the Maltese Islands. It has a strong and fast flight and can be seen both at Chadwick Lakes, in valleys and meadows, and also in urban gardens.
The butterfly has a wingspan of 65 to 86 mm. It has yellow wings, with a net of black veins across them. The hind wings have a pair of protruding tails, like those of the swallow. It is these tails which give the butterfly its common name. Adjacent to each tail, it has one red eye spot with six blue smaller eye sports alongside.
Like all butterflies, the swallowtail butterfly starts its life as a small egg, which the female lays singly on rue or fennel. This hatches after 8 to 10 days, the black caterpillar resembling a bird dropping, helps it to camouflage itself on the food plant. It is only 45 mm in length. To protect itself, the caterpillar also has a large orange fork, which when disturbed, it can extend behind its head, releasing a foul smell.
The caterpillar is a very fast eater. As it grows, it becomes green with black and orange markings. After 6 to 7 weeks, it will attach itself with silky threads to a stem or reed. It will then transform itself into a pupa, which can be either pale green or pale brown. This transformation can take about a day.
The adult butterfly takes from about one to two weeks to emerge from the pupa, depending on the surrounding temperature. If the weather is not warm enough, it can hibernate for several months before it emerges. Within a few weeks it mates and dies. The cycle then restarts again.
