The coldest start to spring for half a century has led to many butterflies emerging weeks later than usual, Butterfly Conservation has revealed.
March, the second coldest since records began, followed a chillier than average winter with snow on the ground in places well into April.
The emergence of many rare spring species was typically delayed by a fortnight and in some cases by three or more weeks, with one species – the Grizzled Skipper, emerging a month later than last year.
Last year the endangered Pearl-bordered Fritillary was on the wing by April 1st but this year the butterfly didn’t emerge until April 27th.
The endangered Wood White was first seen on April 10th in 2012 but this year was not seen until early May. Similarly, Duke of Burgundy didn’t put in an appearance until late April, around three weeks later than last year.
But the late spring is not necessarily a bad thing for our butterflies as the emergence of the host plants they depend upon will also have been delayed.
The cold start to 2013 follows washout 2012 - the worst year on record for UK butterflies with the majority of species suffering declines.
Richard Fox, Butterfly Conservation Surveys Manager, said: “The long cold winter has delayed the emergence of some of our most threatened butterflies by at least two weeks this spring.
“In itself, this is not necessarily a bad thing. The key factor is what the weather is like over the coming weeks while these butterflies are flying, mating and laying eggs.
Many species were decimated by foul weather last spring and their numbers will be lower this year. They really need some fine spring weather and a successful breeding season in order to start rebuilding their populations.
The public can get closer to our rarest spring butterflies this May with Butterfly Conservation.
The charity is running Save Our Butterflies Week - a series of UK-wide events highlighting conservation work that is helping to reverse the declines of our butterflies.
Dr Martin Warren, Butterfly Conservation Chief Executive said: “This is a great chance for people to visit some fascinating sites and see some of our rarest butterflies.
“Experts will be on hand at each event to explain their unique life cycles and the work that Butterfly Conservation is doing to conserve them.”