Summer heatwave may encourage 'tourism' of rare butterflies and bees to the UK, experts say

The sighting of a yellow-legged tortoiseshell butterfly, last seen in the UK in 1953, has confirmed that we are set for an extraordinary summer

The hot weather may have prompted reports of bug infestations, but this summer could also be a great opportunity to spot beautiful rare butterflies and bees not seen in the UK for decades.

Britain looks set to play host to a swarm of insects that are extremely rare – and in some cases new to the country – as the warm weather across Europe sparks a “mass insect migration”, experts said.

The recent sighting of a yellow-legged tortoiseshell butterfly, which has only been seen once before in the UK in 1953, has confirmed suspicions among entomologists that we are set for an extraordinary summer.

“Looking at the weather map, the potential for mass insect movement all over Europe is very real – for butterflies, moths, dragonflies, hoverflies and ladybirds,” said Matthew Oates, a wildlife specialist at the National Trust.

“The arrival of the yellow-legged tortoiseshell raises the question, ‘Whatever next can we expect from migrants this year?’ This is amazing. It’s a very good year to be an entomologist – we’re very worked up this summer.”

The prolonged warm weather is triggering mass insect migration because it provides ideal nurturing conditions which boosts populations. The increased competition for food forces the insects to disperse in search of new supplies, while the rising temperatures make areas that would normally be too cold hospitable.

Steven Falk, an invertebrate specialist at the Buglife charity, said other factors could also contribute. “Strange wind directions related to the high pressure can carry continental insects into Britain and thunder storms can act like hoovers, sucking up insects high into the atmosphere before dumping them hundreds of miles away,” he said.

Other examples of rare insects visiting Britain this summer include the continental swallowtail, which appeared last month to have successfully bred in the UK for the first time since 1945, and the Andrena vaga bee, which was recently spotted in Kent – the first UK siting since 1946. The influx of rare and new species comes against an overall backdrop of rapidly declining insect numbers in the UK and worldwide, much of it due to habitat loss and nerve-agent pesticides known as neonicotinoids.