A spectacular European butterfly has travelled to the UK and for the first time on record, survived the British winter, Butterfly Conservation can reveal.
The Scarce Tortoiseshell, also known as the Yellow-legged Tortoiseshell, is so incredibly rare here that until last year there was just one previous wild record from 1953 - a single female seen at Shipbourne, near Sevenoaks in West Kent.
More than 60 years later and after several sightings throughout the country last July, one has been spotted in Norfolk this month.
Butterfly Conservation’s Head of Monitoring, Dr Tom Brereton, said: “This new sighting is a truly historic event as it marks the first time this stunning butterfly has ever overwintered successfully in Britain.
“The record came in on Thursday 12 March from Holt Country Park on the north Norfolk coast. This area, with its open heathy woodland, provides suitable conditions for the butterfly, which feeds on Birch sap in the spring and lays eggs on willows. The butterfly was still present the next day, but then the weather deteriorated.”
The large and beautiful Scarce Tortoiseshell, Nymphalis xanthomelas, is found from Eastern Europe to China and Japan, but in 2014 an unprecedented migration event resulted in around 30 sightings of the butterfly in the UK, in at least 10 different counties. These were mainly along the East Coast and centred on Norfolk, but some reports came from as far as Devon, Humberside, Tyneside and the West Midlands.
Dr Brereton said: “We've been waiting apprehensively over the last couple of weeks for news to see if any Scarce Tortoiseshells would emerge from hibernation following last year’s mini invasion. The butterfly prefers very cold winters and we weren’t sure if any would survive our mild season.
“If more emerge as we head into spring, 2015 could see the first UK-born Scarce Tortoiseshells on record.”
The butterfly is very similar in appearance to the much-loved garden favourite, the Small Tortoiseshell - one of the first butterflies to be seen this year following a sighting on 2 January in Kent. This butterfly has brown legs and a white patch on the top corner of the upper forewings. The Scarce Tortoiseshell has yellow or straw-coloured legs and a yellow patch on its upper forewing instead of the white.
If you think you have seen a Scarce Tortoiseshell, please email Butterfly Conservation’s Head of Surveys, Richard Fox at @email