PARIS: A plague of desert locusts, which for the past year has been devastating crops in the countries of the Sahel in West Africa, is expected to worsen in the coming weeks if international aid does not arrive to help stop it , say experts with the United Nations Food and Agriculture Organisation (FAO).

If the Schistocerca gregaria's reproductive cycle is not interrupted in October, the locusts will wipe out the grains and vegetables grown in the Sahel and "the infestation could spread to even more countries in Africa, threatening food security in a wide area," said FAO director, Jacques Diouf.

This locust plague is the worst in 15 years and was triggered by abundant rains from June to August 2003 over much of the Sahel, the transition zone between the Sahara Desert and the more fertile lands that lie to the south on the African continent.

Humidity, high temperatures and wind created ideal conditions for the devastating locusts to multiply. From October 2003 to August 2004, the clouds of insects spread through Chad, Niger, Mali, Mauritania and Senegal and through Morocco, Algeria, Libya and Tunisia, in North Africa. New reports from FAO are raising fears that the locusts will reach northeast Nigeria and even Sudan.

Over the past year the plague has destroyed around seven million hectares of farmland - two million in Algeria alone.

The density of insects has reached more than 100 per cubic metre, and their biological cycle was accelerated by rains in the Sahel and adjacent areas since early May.

Normally, the Schistocerca gregaria, despite its name, is a solitary insect. But when its population increases dramatically, it alters its behaviour and moves in large groups to devour vegetables, grains and even the clothing and "jaimas", the tents typical of the region's nomads.

The lines of trees that constitute the "green belt" of the Sahel and protect its central plateau from desertification were almost completely destroyed by the locusts, an unprecedented occurrence.

In just one day, a ton of locusts can consume just as much food as could 10 elephants or 2,500 people, according to FAO.-Dawn/The InterPress News Service.