A worm infestation has largely destroyed 14,700 hectares of grassland in northwest China's Xinjiang Uygur Autonomous Region, and pastures were cordoned off Thursday for 10 days to allow workers to spray pesticide.

The outbreak is threatening grass supply to more than 200,000 heads of livestock owned by more than 200 households.

The dark worm, known as Entonmoscelis Adonidis Pall, has infested the pastures in Shawan County, Tacheng District, about 180 kilometers north of Urumqi, the regional capital, said Zhao Dengke, vice director of the locusts and rodents control station in the district.

Herders have been told to take their livestock to unaffected pastures while the spraying is in progress.

Among the 14,700 ha of affected grassland, 8,000 ha were seriously damaged, leading to a 50 percent decrease in grass output and an estimated loss of 1 million yuan (about US$146,500) this year, said Li Zhixin, head of the county's pasture working station.

The worms, which are 1 to 2 cm long, are so numerous that there are up to 3,000 per square meter, Li said.

The county has more than 553,000 ha of pasture and crop land, including about 200,000 ha in southern Shawan.

The past warm winter and frequent rainfalls this spring provided a favorable breeding ground for the worms, Zhao explained.

The county experienced scattered worm outbreaks in 2004 and 2007. A locust infestation last year caused 3 million yuan in losses.

Earlier this month, an 8,000 ha pasture in Shawan's neighboring county of Usu experienced an infestation of unidentified worms, forcing about 20,000 head of livestock and 50 migrant families to leave earlier than planned.

That grassland had turned pest-free as of Wednesday and will be open to grazing in the autumn, according to an official in charge of grassland management.

(Xinhua News Agency May 22, 2009)