BUTTERFLIES and bees have struggled in the latest year of a decade of unsettled weather, the National Trust has said.

In its 10th annual appraisal of the UK's wildlife and weather, the trust said mild winters and "pulses" of bad weather in the summer months were becoming the norm - including in Somerset - with impacts on many species.

The impacts were seen at sites owned by the trust including Lytes Cary, Somerset, where bumblebee numbers plummeted by some 85 per cent on the previous year as wildflowers in field margins were outgrown by grass.

The UK has not had a good summer since 2006, according to the trust's nature and wildlife specialist Matthew Oates.

In 2016, a mild winter, cold spring and mild, wet conditions in May and June have led to a bumper year for grass growth.

The conditions spelt good news for farmers with livestock and for making hay and silage, but created difficult conditions for small plants and wildflowers that were squeezed out and insects such as meadow butterflies which feed on them.

Meadow butterflies struggled on Purbeck, Dorset, with marbled white numbers falling by three quarters (73 per cent) on the previous year and volunteers spotting 23 per cent fewer common blue butterflies.

Wasp numbers appeared to have crashed in many places in recent years, which may be welcome news to picnickers and visitors to National Trust tea rooms.

But their absence could have a negative impact on the food chain, where they play a useful role eating pests and providing food for other species.

Mr Oates said: "2016 comes on top of an unsettled decade, with many species struggling in the face of climate change and more intensive farming practices."

"In the 10 years we've been reviewing wildlife at our places we've noticed pulses of unsettled weather become the norm."

And he said: "When you do get good weather during the brighter months of the year, it's almost inevitably short-lived and finished with something nasty.

"During the brightest months, we do seem to be getting more extreme weather events, most of which aren't nice."

The conditions could do damage to species such as wasps and butterflies, with knock-on effects on insects, birds and bees that feed on them.

There were good hay and silage harvests for National Trust tenant farmers and estates, as well as some localised successes to boost species, with rare cirl buntings numbers up 800 per cent since 1989 in Cornwall and Devon.

And grazing by rare-breed Longhorn cattle in the Lake District's Ennerdale Valley has provided the right wet grassland habitat for marsh fritillary butterflies, with larvae numbers up 560 per cent in 10 years.

Mr Oates said much of the UK's rare species and habitats such as grassland and heathland was dependent on grazing by domestic livestock, highlighting the importance of conservationists and farmers working together to deliver land management.

And funding for conservation through wildlife-friendly farming payments should not be lost post-Brexit, the trust said.