Rats!

"Flowering of a ubiquitous bamboo, Melocanna baccifera, in the Indian state of Mizoram occurs in roughly fifty year cycles. This mass flowering event results in the production of innumerable bamboo seeds and, subsequently, a boom in the population of rats. The mass population of rats eat more than the bamboo seeds, however — food crops are devastated causing famine and political unrest." (thanks D. who found the title too)