IN THE jungle-clad hills of northeastern India, they call it simply mautam.

Once every 48 years, the bamboo forests that cover much of the region burst into flower, scatter their seeds, then wither and die within a few months. The mysterious phenomenon, known as “gregarious flowering”, is happening this year, in the state of Mizoram, on the Indian border with Burma.

For botanists, the simultaneous sprouting of the tiny pink flowers is one of the wonders of the natural world and a once-in-a-lifetime opportunity. For farmers in the area, it means only one thing — famine.

According to local folklore, the blossom heralds a plague of rats that will sweep across the area, devouring rice fields and granaries. This year appears to be no exception. In the past two weeks, swarms of rats — tens of thousands at a time — have been attacking paddy fields, often destroying several acres in a few hours.

Local officials are braced for massive food shortages next year, when the bamboo blossom is expected to reach its peak. “There is a real danger of a famine,” James Lalsiamliana, an agricultural scientist in Mizoram’s government, told The Times. “When the bamboo flowers, there is a sudden increase in the rat population and the rats destroy the paddies. They come in a group in the night, with a sound like the wind, and finish off an entire field in a few hours.”

The precise link between the bamboo flower and the rats remains a mystery but bamboo blossom has been seen as a bad omen for thousands of years: it is even described as such in The Mahabharata, the Sanskrit epic that dates back to 500BC.

Recent history lends credence to the superstition. The last flowering in Mizoram, in 1958-59, caused a famine that killed between 10,000 and 15,000 people and destroyed hundreds of thousands of livelihoods.

It also prompted the formation of the Mizo Famine Front, which evolved into the Mizo National Front, one of several separatist movements in India’s volatile northeast. The flowering before that, in 1911, triggered another devastating famine, and the blossom of 1862 had similarly dire consequences.

Scientists from around the world have studied the cyclical disaster in vain, but local experts have come up with a rough explanation. All bamboo plants have a life cycle of between 30 and 60 years, compared with a few months for rice or wheat. Mizoram’s bamboo strain lives for 48 years. The bamboo is thought to flower simultaneously because a single plant spreads over huge areas, with its offshoots sharing the same genetic code.

When the flowers turn to fruit, the rats in the forest feast on the protein-rich seeds, causing an explosion of their population.

“It’s only an assumption, but we think it’s because the seeds are highly nutritious,” Rosiama Vanchong, an officer for bamboo development in Mizoram, said. “Once the seeds are eaten, the rats go in search of food not available in the forest.”

About 5 per cent of Mizoram’s 6,644 sq km of bamboo forest is now in flower and local officials expect the figure to hit 100 per cent by next June. To prepare for the coming crisis, they are distributing rat poison to villages in the region, but they admit tht it is a losing battle. The only way to avoid famine, they say, is to get farmers to grow fruit and root crops that rats cannot eat.

“There’s no way we can kill all the rats,” Mr Lalsiamliana said. “We don’t know where they come from, or where they go to.”

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