Rising water levels in China's second-largest freshwater lake have propelled a massive rat migration from the lake's islands into nearby farm fields - creating the area's gravest rat crisis in 10 years.

　　Since May, rodents leaving Dongting Lake in central China's Hunan Province have nibbled countless crops, destroying thousands of hectares of produce.

　　The rat disaster has ravaged a fertile farm area. The climate in the Dongting basin is temperate, and rainfall is plentiful. The alluvial plain around the lake makes it one of China's major rice and cotton bases.

　　In past years, the plain was filled with early season rice and the smell of melons in June. But recently, a Xinhua reporter who visited Nangang Village in Yuanjiang City's Chapanzhou Township encountered large areas of devastated rice.

　　Walking along the field's ridges, the visitor said hordes of rats leaping from the weeds. The farmers often stopped their work to drive away the rats with wooden sticks.

　　But the efforts appeared to be futile. There were too many rats, and they moved too fast.

　　"A great number of field rats that lived on the islands of Dongting Lake migrated to the farmland due to the rising water level of the lake. The rats live on the roots and stems of both the grass and crops, and the rice seedlings are delicacies to them," said Wang Yong, a researcher at the Chinese Academy of Sciences.

　　According to the township's vegetation protection station, there are about 300 to 500 rats in each mu (0.067 hectare) of farmland. In some of the fields, the number exceeds 1,000.

　　The local vegetation protection station said that in some places there are 10 to 15 rats per square meter. "Our family has three mu of early rice. In the past each mu could produce more than 400 kilograms of rice, but this year we may gain nothing," said Zhang Guocai, a farmer in Suhutou Village.

　　Villager Wu Chuanxi also suffered major losses.

　　"We have nearly three mu of paddy, but one-third was destroyed by the rats within just a few days" Wu said. "The rats are just like thieves in the night."

　　Other crops such as pumpkins, watermelons, cotton and aspen seedlings were also involved in the disaster, said Liu Guoteng, vice Party secretary of Yuanjiang City.

　　Chinese Academy of Sciences researcher Wang Yong said the rat migration is the most serious in the area since 1995.

　　The local government is offering bounties in the attempt to bring the disaster under control.

　　Xinhua reporters saw officials counting rat tails at a government building in Shapanzhou Township. An official said farmers are being paid 0.2 yuan (2 US cents) a tail and had handed in more than 1,000 so far.

　　Experts said the field rats reproduced at a high rate on the islands of Dongting Lake in recent years due to the lake's long-time low water level. But the rising water levels drove the pests to the nearby farmland.

　　When the water returns to its former state, another massive migration will take place when the rats return to the lake islands, the experts said.

　　(Xinhua did not explain why the lake level was changing.)

　　Wang said the governments around Dongting Lake should establish a regular monitoring and reporting system on the rat situation. Meanwhile, experts are warning epidemic prevention departments to be on the alert for rat-borne diseases.

　　(Xinhua)