Sussex Butterfly Conservation : Species

Butterfly Species in Sussex

An egg-laying Swallowtail – photo by Philip Booker

Swallowtail

Papilio machaon gorganus

Description

A Continental Swallowtail is high up on the list of species that many butterfly enthusiasts would like to see, but for most of us this wish is unlikely to be granted.

Unlike our British subspecies britannicus which has a single brood and stays at home, gorganus is double-brooded, and it is strongly migratory. This means that every year we have the possibility of two influxes, “from late May to early June and again from Mid-July to mid-August” (Pratt, 1999).

This species does occasionally breed in Sussex, and it is worth re-visiting the events of 2013-2014. A few Swallowtails were recorded in 2013 and this led to the discovery of Swallowtail caterpillars and pupae. Some 13 pupae at various sites across the county were monitored over the course of the winter and the following spring. They were left outside but protected from bird predation. Michael Blencowe (and others) wanted to see if they could survive a Sussex winter. In 2014, at least 11 butterflies were either seen to emerge or recorded nearby. They emerged over a period of 18 days, between May 18th and June 5th. Butterflies were seen at Chichester, Peacehaven, Chanctonbury Ring, Broadbridge Heath and Steyning Downs.

The dates are important, for it means that records in the second half of May or the first week of June could be immigrant or “home-bred”.

For the years 2006-2024, the best month to see gorganus was August. Unusual late records included 02/09/2019, 10/09/2015 and a remarkably late sighting on 13/11/2016.

Most records are within 10km of The English Channel, either on the coastal plain or on downland. This is one of those species that engages in “hill-topping” , and if we are lucky, we may find a Swallowtail on a high point somewhere along the South Downs.

The larval foodplants are mostly Wild carrot and Wild Fennel and within Sussex these plant species are most abundant in the coastal plain and the South Downs (which may be one reason why most records are within 10km of the coast?). Equally, this butterfly may be found in vegetable gardens and allotments, as cultivated carrots and Green Fennel are also used for egg-laying.