The scientific numbers are not yet in from the UK Butterfly Monitoring scheme, but the Big Butterfly Count recorded its worst figures since it began

At first glance, it has been a bafflingly bad summer for butterflies. After a decent spring in the north-west and a dazzling late summer in the south-east, garden buddleias remained bereft. The only butterfly I’ve seen in good number is the red admiral, which thrived during the second-warmest September on record.

The scientific numbers are not yet in from the UK Butterfly Monitoring scheme (a magnificent dataset collected by 2,000 volunteers each summer which celebrates its 40th birthday this year) but the Big Butterfly Count recorded its worst figures since it began – worse than the washout of 2012.

“Because the summer weather wasn’t anything like as bad as 2012, the finger is pointing at the mild, wet winter,” says Matthew Oates of the National Trust.

Most of us probably don’t consider last winter an “extreme” event, but it was wet and violently mild. December 2015 was the warmest ever in the Met Office’s Central England Temperature series stretching back to 1659. It’s the most anomalous month ever recorded – 5.1C above average, more than double the ordinary monthly average.

We may have barely noticed last December, but butterflies did. Caterpillars emerged from their diapause, found nothing to eat and perished.

“The interesting thing is the species that did worst this summer are generally those that spend the winter as larvae,” says Oates: the purple emperor, silver-washed fritillary and white admiral all struggled this year.

We need more scientific research on the impact of mild, wet winters, but such correlations are fiendishly difficult to prove. “It’s scary,” says Oates of the mysterious impact of extreme weather.

Small children won’t be the only ones wishing for snow this winter. Butterfly lovers will be too.