The painted lady butterfly, which has orange, brown and white markings, could also enjoy a record year.Butterfly Conservation is urging people to help monitor the common blue by taking part in the Big Butterfly Count population survey.Dr Randle added: “It would really help us if people could get outside and look for this butterfly, so we can see if its fortunes really have turned around.”Participants are asked to spend 15 minutes counting every butterfly they see before submitting sightings at bigbutterflycount.org until August 11. The population of the common blue butterfly is expected to boom because of record heatwaves.Experts believe the insect may be enjoying its best ever summer, due to soaring temperatures in July and an above-average forecast for this month.The common blue has been struggling for 40 years, according to the Butterfly Conservation charity, but last summer the population increased by 104 per cent thanks to warm weather.Overall, butterfly numbers rose by 110 per cent in England last year, compared with 2017, and 94 per cent in Wales, according to the charity. The long-term trend had seen three quarters of species decline since 1976.Butterflies are particularly sensitive to climate change and destruction of habitats. Any decline in numbers is a clearly visible early warning sign of wider insect loss, experts say. Without butterflies, birds that rely on them for food and plants that depend on them for pollination will die out, leading to a knock-on effect further up the food chain.The male common blue has bright blue, unmarked wings, whereas the female is decorated with orange crescents and dark spots near the wing-tips, with a tinge of blue closer to the body.Dr Zoe Randle, a senior surveys officer for the charity, said: “People should be able to spot these butterflies in National Park areas as their caterpillars mainly feed on the wildflower common bird’s foot trefoil.” Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings.