Swarms of desert locusts rampaged across West Africa this year, stripping crops and crippling countries already hit by food shortages. Unusually rainy weather created perfect conditions for the insects to lay their eggs in damp, sandy soil every two or three months, swelling their numbers tenfold with each new generation. Scientists fear that locusts will keep breeding uncontrollably over the winter and emerge in even greater numbers next spring. “It’s the most serious situation we’ve seen in the last 15 years,” says Keith Cressman, an entomologist at the Rome headquarters of the Food and Agriculture Organization of the United Nations.
Locust plagues have stricken Africa sporadically for more than 6,000 years. When the insects reach a critical mass, they start gathering together, first forming carpets of immature nymphs and then winged throngs that can span hundreds of square miles. A swarm can blacken the sky, fly as far as 120 miles in one day, and strip a field overnight. The plague this past year followed a circuitous path from Mauritania in the west to Morocco and eventually reached the Mediterranean coasts of Libya and Egypt. Countries are battling the invasion with pesticides sprayed from planes and trucks. But stamping out locusts is tough because the areas to be treated are so vast, and many countries lack the money and equipment. Exactly how much the situation deteriorates will also depend on the weather; the last plague, which began in 1987, ground to a halt in 1989 partly because freak winds gusted swarms out into the Atlantic—as far as the Caribbean.