The UK is enjoying a once-in-a-decade “painted lady summer” when huge numbers of the migratory butterflies arrive and breed here, conservationists have said.

Wildlife charity Butterfly Conservation is urging members of the public to count the painted ladies they see as part of its annual Big Butterfly Count, which helps experts assess how butterflies are faring each year.

The charity says warm weather across Europe this spring prompted millions of painted ladies to flock to the UK, with clouds of butterflies seen feeding and mating in some spots, and their offspring are now emerging around the country.

The profusion of butterflies points to a “painted lady summer”, which only occurs around every 10 years and sees soaring numbers of the insects with distinctive orange, black, and white patterned wings.

placeholder image — A Painted Lady butterfly.

The migration the painted ladies undertake from sub-Saharan Africa to Europe is one of the world’s longest insect journeys, and takes successive generations to complete – so that the painted ladies which leave Africa are not those that arrive in the UK to breed, experts said.

Adults born in sub-Saharan Africa during the winter fly to north Africa where they mate and lay eggs, with those offspring then migrating across the Mediterranean Sea to southern Europe and mating and laying eggs.

The generation which was born in southern Europe in turn arrived in the UK in late spring, mated and laid eggs, and now a new generation of “home grown” painted lady adults is emerging across the country.

Butterfly Conservation said this year is on track to be the third best year for painted lady numbers on record, after 1996 and 2009, but that will depend on the numbers over the coming weeks.

So nature lovers are being urged to count painted ladies, along with other butterflies they see, as part of the Big Butterfly Count.

Last year in the annual count, people around the UK reported a total of 15,856 painted ladies – but the last time there was a painted lady summer, in 2019, the total was more than 420,000.

Butterfly Conservation said this year’s numbers are already significantly higher than last year, and higher than the same point in 2019, suggesting this year’s painted lady summer could dwarf the last one.

Butterfly Conservation head of science Professor Richard Fox said: “The inter-continental migration of painted lady butterflies is a wonder of the natural world and one of the longest insect journeys on the planet.

“The numbers we’re seeing here at the moment have already dwarfed the total number of painted ladies we saw last year, and we’re absolutely delighted.

“With their beautiful pinky-orange, black and white patterned wings, they are one of our most popular species.

“The new generation of painted ladies is emerging across the UK right now prior to flying the next leg of the species’ epic journey, and helping to count them is a great excuse to take part in this year’s Big Butterfly Count.”