The number of butterflies spotted in the wild has fallen this year, while bumble bee numbers have been halved, putting the pollination and survival of certain plants in danger, experts have warned.

The results of the spring butterfly count have shown the average number of butterflies has gone down by 20 to 30% compared to preceding years, making 2023 a particularly bad year.

“The number of butterflies spotted in 2023 is clearly below the average, and so far this year has been the worst since the count began in 1990,” the butterfly protection society Vlinderstichting said.

Bumble bees have also had a bad start this year. “Sightings were down 50% at the end of May,” Johan van ’t Bosch of insect knowledge centre EIS told NU.nl.

Experts are hoping the wet weather kept the bees from view but the more likely scenario is that numbers have been affected by last year’s dry summer which limited nectar and pollen supplies.

Insect habitats, often in areas bordered by motorways and agricultural land, have been under threat from nitrogen pollution, insecticides and poor water management, biologists have said, putting rare and vulnerable species at risk.