In the wild in Britain this lovely butterfly is a very rare sight, confined to parts of the fens of Norfolk. In southern England, where occasionally specimens stray from northern France, the preferred habitat of this large, colourful butterfly is damp wildflower meadows. Elsewhere in Europe it frequents woodland edges and gardens, too.
The Swallowtail is a large butterfly; its wingspan is typically between 9 and 10cm.
With climate change this once rare visitor to Britain may eventually be seen rather more often, but at present it is still unusual to see a Swallowtail anywhere except for the occasional migrant in the south-east of England.
Swallowtails are a very common sight on mainland Europe and the Far East. The specimen shown above was photographed in the Algarve near Aljezur, on the west coast just north of Cape St Vincent.
In most countries the Swallowtail produces two broods, the first in May and early June and the second in August. Butterflies that emerge in early summer lay their brown eggs singly on the upper leaves of Hog's Fennel, also known as Milk Parsley (Peucidanum palustre). Caterpillars emerge after about a week; they are black with white band.
By July, when the first-brood caterpillars are fully grown and ready to pupate, they have turned bright green and are ornamented with narrow black bands and orange spots. The larva shown here was photographed at Benagil, on the Algarve in southern Portugal. (Picture: Rob Petley-Jones)
The chrysalis, which may be either pain green or pale brown with a darker brown stripe, is attached to the stem of a reed. In this form the insect hibernates until the following year.
If you found this information helpful, you would probably find the new 2017 edition of our bestselling book Matching the Hatch by Pat O'Reilly very useful. Order your copy here...