Locust horde threatens Pakistan's prized cotton farms.

"We're finished, nothing is left!" says farmer Vikram Meghwar pointing to millet stalks raided by swarms of locusts.

Like others in the village of Amarhar in Umerkot district, at the edge of the Tharparkar desert, the Meghwars, a farming family, clanged tins and made as much noise as possible during the day, hoping to chase away swarms of locusts from their millet crop. At night, they lit smoky fires, but nothing deterred the voracious, yellow pests, which arrived in the village last month.

According to the Food and Agriculture Organization (FAO), the locust infestation in Pakistan and the neighbouring Indian state of Rajasthan will persist throughout October and then move into south-eastern Iran and Sudan because of unusually extended monsoon rains.

The summer precipitation was unpredictably long and intense, says Tariq Khan, technical director at the Ministry of National Food Security and Research's Department of Plant Protection, attributing the invasion to unseasonal moisture caused by climate change.

"Moisture in the atmosphere, sandy soil and vegetation were perfect for the locusts," explains Khan.

After three years of arid conditions, Umerkot saw pouring rains this season, recharging the wells and pushing up tall grass. Encouraged by the moistness of the soil, the villagers sowed their crops and were about to reap a bountiful harvest when the locusts struck.

A swarm (between 30-50 million locusts) can devour 200 tonnes of food in a day. They can also fly a distance of 150 kilometres to search for more food. Pakistan last saw locust attacks on this scale in 1993. "Once they have devoured the desert vegetation, they head for the crops,' says Khan.

"The air turns thick with these yellow-coloured insects so that the sky darkens even when the sun is blazing, it's quite surreal," says 40-year-old Akber Ali, a school teacher in village Viklokar, whose crop of cluster beans on three acres miraculously escaped the pests.

Being a rainfed region, the people cultivate crops only if it rains, says Zahid Bhurgari, general secretary of the Sindh Chamber of Agriculture, the biggest farmers' organisation in Sindh. He estimates that 5,000 acres of millet, moong (green gram) and sesame have been destroyed.

Khan has been following the pests since early this year, when the swarms were first sighted on the Yemen-Saudi Arabian border. "Because of the war in Yemen, no effort was made to control the swarms and they traversed Saudi Arabia and Iran to enter...