People are being encouraged to count the number of butterflies they see over the next three weeks as part of an effort to save them from extinction.

Two-fifths of butterflies in Britain are under threat according to Butterfly Conservation

BBC News report that the charity is encouraging the public to spend 15 minutes outside counting the number and type of butterflies spotted.

This can help assess the effect of climate change and pollution once figures are collected.

The annual Big Butterfly Count is backed by naturalist Sir David Attenborough - the charity's president - as well as actress Joanna Lumley and gardener Alan Titchmarsh.

The National Wales: The annual Big Butterfly Count is backed by names including Sir David Attenborough (Canva)The annual Big Butterfly Count is backed by names including Sir David Attenborough (Canva)

BBC News report: "The event will help scientists understand how environmental changes are affecting insects, and gather data from areas that would otherwise be unrecorded, experts said."

The count will run from July 15 to August 7 and counts can be sent into the charity at their website here.

Dr Zoe Randle, senior surveys officer at Butterfly Conservation, said: "Thanks to the wonderful British public, the Big Butterfly Count is the largest natural history citizen science project involving insects in the world and provides us with a valuable snapshot of what is happening for butterflies.

"It can act as an early-warning system, letting us know how various environmental changes are impacting insects, and allows us to gather vital data from places that would otherwise be totally unrecorded."