China building new Great Wall against rats

China is building a new Great Wall-a relative miniature at 1 meter high-to guard against hordes of pillaging mice. Lujiao, a town in central Hunan province that was overrun by field mice last month, is erecting a 40 km barrier around Dongting Lake to keep the rodents away. About 2 billion mice nesting on the shores of China's second largest freshwater lake gnawed their way through 5,20,000 hectares of crop land when rising water drove them from their burrows. Such plagues underline China's growing struggle to maintain a stable environment, said Yang Hualin, director of the Chinese Pest Control Association in Beijing.

"These are alarm bells amid China's economic development," Yang said. "Ultimately, the original ecological balance needs to be restored, but at the moment that's going to be hard." The country must build up the population of predators, such as owls, snakes and weasels, which have dwindled because of farming and the use of poison to contain pests, he said. "At the moment, this is the only thing that can be done," Yang said of the wall.

However, walls won't shield farmers from the next mouse plague, said Wen Bo, director of the China programme at Pacific Environment, a conservation group in San Francisco. Mice will find holes in the cement-and-rock fortification and resume their assault, he said. "The wall is a symbolic gesture to quiet public concern," Wen said. "It's not going to work in the long run." In Binhu, a hamlet administered by Lujiao, Zhang Shouliang said she and her neighbours used bamboo sticks to kill thousands of mice that invaded their homes and crops.

Her extended family of 13 lost its entire harvest of corn, peanuts and watermelon, worth 10,000 yuan ($1,300). Climatic conditions aggravated this year's plague, said Zhang Meiwen, a Hunanbased researcher from the Chinese Academy of Sciences. Dongting's waters receded to lower- than-usual levels after a dry winter, giving mice more room to breed. After authorities at the Three Gorges Dam opened sluices to alleviate flooding upstream in the Yangtze River in mid-June, the lake began rising by as much as half a meter a day, driving mice into 22 surrounding communities, Zhang said.

"This is the prelude of a battle between mice and men," the Institute of Subtropical Agriculture said about Hunan's plague. The Lujiao government is raising 6 million yuan for its wall, the state-run Xinhua news service reported. China's Great Wall, built from about 220 B.C. to fend off pillaging tribes from the north, extends more than 6,400 km. The wall, which stands 8 m tall in some parts, didn't halt Genghis Khan, who sacked what is now Beijing in the early 13th century. But optimistic Zhang said: "Once they get the wall built, we'll be better off.