Police are planting covert cameras on Lincolnshire farms after a spate of arson attacks on straw stacks.
More than 10 farms have been targeted in South Lincolnshire in the past two months, prompting the police operation to attempt to catch the arsonists on camera.
Farmers have been urged to locate their stacks away from roads as the arsonists are believed to travel by car.
At the time of most of the arson attacks, the bales were stacked in fields and adjacent to roads, ready to be delivered to Elean straw-burning power station at Sutton, Cambridgeshire.
A police spokesman said stacks had been set alight in several villages around Bourne.
“We are liaising closely with local farmers and providing them with information on incidents as they come in via the Farmwatch email system,” he said.
“We urge all farmers in the area to be vigilant and report any suspicious sightings or vehicle movements.”