It is feared Yorkshire’s moorland could lose its distinctive purple heather due to swarms of beetles.
The heather beetle has been blamed for moorland turning from purple to shades of orange and brown.
The insects have thrived after the “Beast from the East” weakened resilience in plants, said the Moorland Association.
The warning coincides with the start of the grouse shooting season, with Labour calling for a review of the sport.
“There are swarms of these larvae and they can munch acres and acres and acres,” said Amanda Anderson, Moorland Association director.
She said the “infestation” had affected both grouse, which depend on moorland for food, and bees.
The Moorland Association, whose members manage a million acres of uplands in England and Wales, describes grouse shooting as a source of significant income for rural economies.
However, the Labour Party says the process of draining land in preparation for the shooting season destroys “huge swathes” of plant life and kills large numbers of animals.
The North Yorkshire Moors Moorland Organisation, created by a group of gamekeepers to promote shooting estates, also reports an “increased problem” with beetles.
The organisation’s co-ordinator Tina Brough said gamekeepers could speed up the recovery of heather by carrying out controlled burning, although this might not be possible with large areas of land.
The increase of heather beetles – or lochmaea suturalis – could be due to a cold spell last year, nicknamed ‘“Beast from the East”‘.
Elspeth Ingleby, ecologist at North York Moors National Park Authority, said last year’s long, dry summer was was “terrible” for the heather but “this year looks set to be significantly better”.
“We hope that those areas of the national park that look to be affected by heather beetle still have more to give this year in terms of their colour,” she added.