A scientist is warning of a second wave of invasion by field mice fleeing floods in the Dongting Lake area in Hunan province, despite an official claim that the mouse plague was under control. Two billion mice have already fled their nests. Zhang Meiwen, a deputy research fellow of the Chinese Academy of Sciences' Institute of Subtropical Agriculture, said if water levels at Dongting kept rising 'an even fiercer onslaught of mice would follow'. Water levels could easily rise, as the monsoon season is forecast to last until the end of this month and more rain is expected in coming days. Hundreds of farmers have been mobilised since late last month in a desperate attempt to fend off the invasion of field mice searching for drier ground. The invasion, the biggest recorded, threatens paddy fields, dams, dykes and other major infrastructure. The central government has pledged 10 million yuan to fight the rodent plague but, according to mainland media, farmers living near the lake have criticised authorities for not responding soon enough to the crisis - forcing farmers in some areas to buy rat poison on the black market. Dr Zhang said most farmers had been offered little information on how to fight the plague and had resorted to poison for quick results. But the abuse of lethal poisons could be a disaster for the local ecosystem because many of the mouse's natural predators would die from eating the poisoned mice. He also said mice easily developed resistance to poisons, making it more difficult to contain the plague. He said his institute had warned governments in Hunan about a looming rodent invasion as early as May. 'The impact of the mouse plague could have been far smaller if precautionary measures had been well in place,' he said. The plague has been exacerbated by a lingering drought, which cut water flow to the Yangtze River in the past year, giving mice more time to breed. But Dr Zhang said the Three Gorges Dam on the Yangtze and an unbalanced ecosystem were also to blame. The gigantic dam had altered water flow to the lake and the pattern of flooding, allowing the mice to breed more freely than before, he said. The catching of snakes for food - many locals consider the reptiles a delicacy - had also helped the mouse population flourish. 'The long-term solution is to restore the ecosystem in the lake areas,' Dr Zhang said. Authorities said there had been no reports of outbreaks of infectious disease near the lake.