Painted lady butterflies emerge in once-a-decade phenomenon

By Carol Duncan
BBC Scotland News

Media caption,
Painted lady butterflies have been seen across the country

Large clouds of painted lady butterflies are being spotted across the UK and Ireland - and experts believe we are seeing a mass emergence that happens every 10 years.

Weather conditions and food sources are providing ideal conditions for the species to thrive.

Sightings of painted ladies - otherwise known as Vanessa cardui - have prompted countless pictures and videos to be posted to social media.

About 11 million of the butterflies were seen in the UK during the last "painted lady year" in 2009.

Image source, Eileen Kerr
Image source, Lynsey Wilson

Simon Milne, Regius Keeper at the Royal Botanic Garden in Edinburgh, describes the phenomenon as "an amazing wonder of nature".

On a normal day, in a regular year, Simon said he would expect to see about 10 to 15 of the species at the botanic gardens.

But he has encountered thousands of painted ladies in the past few days, and predicts that this year could see bigger numbers than ever before.

We are currently seeing a wave of home-grown butterflies, which are the descendants of those carried on winds from sub-Saharan Africa, along with newer arrivals from continental Europe.

Image source, Richard Palmer
Image source, Linda Smith

Despite their delicate appearance, the insects can cover up to 100 miles each day as they migrate.

Painted ladies complete their life cycle in five to eight weeks. It can take up to six generations to make the annual migration, leaving Africa in April to head north and returning once cooler weather settles at this latitude.

Tom Prescott, senior conservation officer with Butterfly Conservation Scotland, says that favourable breeding conditions mean we could see another wave of butterflies at the end of the summer "come early autumn, we could be up to our knees in them," he said.

Numbers depend on favourable conditions earlier in the year, where the butterflies spend winter, warmer temperatures and favourable wind conditions as they migrate north.

Common Blue comeback

The species often lay eggs on thistles, giving them the name Thistle Butterfly. Adults tend to feed on flowering plants and are often attracted to buddleia plants.

The public is being asked to submit butterfly sightings online to help Butterfly Conservation monitor numbers of this and other species.

Many butterfly species have been in decline.

According to the Butterfly Conservation Society, there is "evidence of the serious, long-term and ongoing decline of UK butterflies".

However, the society believes the Common Blue could be making a comeback.

During 2018's record-breaking hot weather, numbers increased in Scotland by 29% on the previous year. They are now predicting the butterfly could be in line for its best year yet.

The society's five-yearly research - last published in 2015 - indicated 70% of species declining in occurrence and 57% declining in abundance since 1976.

All pictures are subject to copyright.

More on this story