Butterfly numbers in the Netherlands have more than halved since 1992, with the spring and summer of 2023 the worst year so far, figures from statistics agency CBS have shown.

The decline had set in before then, with species like the purple-edged copper, the poplar admiral and the small blue disappearing in the 1980s or earlier.

Changes in the landscape, drought and wildflowers wiped out by too much manure are the main reasons why meadow butterfly numbers in particular have been falling, experts say.

“In spring 2023 I was walking through an area rich in flowers and I saw exactly two butterflies,” Kars Veling of the butterfly conservation association Vlinderstichting told broadcaster NOS. Association volunteers check several routes across the Netherlands to compare sightings over the years.

“I  didn’t see any butterflies in my garden for six weeks in the spring of last year,” his colleague Anthonie Stip said. “The summer was slightly better for some species but for many it was very thin.”

Relatively common species, like the small tortoiseshell, the green-veined white and the large white are also significantly down in numbers, the Vlinderstichting has found.

Many meadow species have now been relegated to roadside verges but there too their existence is precarious because of verges get mowed Stip said. It would help if once mowed the debris is not left to accumulate and stifle the growth of wildflowers on which the butterflies depend, he said.

Mowing should also be phased so the butterfly can safely complete its complete cycle, from caterpillar to chrysalis to butterfly. “Butterflies need places to hide and feed at each stage of their development,” Stip said.

“But if butterfly populations are to recuperate we need more nature-inclusive farming but until then proper ecological management of roadside verges may slow down their decline.”.