Swarms of pests including spiders and aphids have severely damaged more than on e million hectares of cotton fields in northwest China's Xinjiang Uygur Autonomous Region, officials have said. Damage estimated at $85m is believed to have been caused by the pests to the northern part of the region, which includes Bortala Prefecture, Shihezi City and Usu County, vice director of Xinjiang General Station of Plants Protection claimed.