A rare and spectacular butterfly may be attempting to colonise the UK after adults recently emerged on the south coast, Butterfly Conservation has revealed.

A dozen adult Continental Swallowtail butterflies Papilio machaon gorganus have been seen across Sussex in the last few weeks after successfully overwintering in the UK.

Last year’s hot, sunny summer saw the largest continental Swallowtail invasion since 1945 with adults laying eggs in a number of gardens in Hastings, Eastbourne and Chichester. 
The butterflies were also seen in other south coast counties including Suffolk, Kent, Hampshire and Dorset.

Swallowtail ssp underwingThe UK’s relatively cold climate makes it very difficult for the butterfly to survive through the winter but the recent successful emergence of adults suggests last year’s breeding attempts have been successful.

The large Continental Swallowtail resembles a tropical species with dramatic yellow and black markings and distinctive streamer-shaped tail.

The UK boasts its own subspecies of Swallowtail Papilio machaon britannicus which despite being our largest native species is smaller and darker than the continental butterfly and is now restricted to the Norfolk Broads.

The warming climate raises the possibility that the striking Continental Swallowtail may potentially become a UK resident in the near future.

Michael Blencowe from Butterfly Conservation’s Sussex Branch has been monitoring the butterflies since they arrived last summer.

He explains: “So far there have been 12 sightings of Swallowtails in Sussex this spring. Six of these have been seen to emerge from pupae we were monitoring; others have been seen in Peacehaven, Chichester, Chanctonbury Ring and Horsham. 

“There are still more to emerge and no doubt many other Swallowtails that we don’t know about are roaming the country, so there has never been a more exciting time to head out looking for butterflies.

“This current invasion could be the start of the colonisation of Southern England by the Swallowtail. In 20 years this butterfly could be a regular visitor to our gardens.

“We’d be interested in hearing of any Swallowtails seen in Southern England. Please send details of your sightings to Michael Blencowe @email