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EO Study: Locust! Page 2


The Reach of the Desert Locust

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Tens of millions of square kilometers of crops and rangeland in northern Africa, the Middle East, and Asia are within the reach of the desert locust. The livelihood of at least one-tenth of the world’s population can be affected by the small insect with its voracious appetite. A single swarm can cover 1200 square kilometers (460 square miles) and can contain between 40 and 80 million locusts per square kilometer. With each insect capable of eating its own body weight (about 2 grams, or .07 ounces) in vegetation each day, a swarm that size could consume 192 million kilograms of vegetation each day, or more than 423 million pounds. Now consider that in the last century alone, there were seven periods of numerous plagues, the longest of which lasted intermittently for 13 years.


Photograph of Feeding Locusts

Crop and rangeland damage due to locusts is a great threat to regional and global food security, and efforts have been underway for decades to control the formation of desert locust swarms. Over the years since World War II, the United Nations Food and Agriculture Organization (FAO) has emerged as the leader in the effort to predict, prevent, and control locust plagues. Along the way, they have had help from remote sensing ecologist Jim Tucker at NASA’s Goddard Space Flight Center. In the early 1980s, Tucker’s long-time interest in desert ecology led him to collaborate with FAO scientists on using satellite data to predict where and when locust plagues were likely to break out.


Locusts can consume roughly their own weight of vegetation each day—swarms of millions will strip crops bare in hours. (Photograph courtesy Compton Tucker, NASA GSFC)


Map of
Locust Distribution

During quiet periods, called recessions, locusts are confined to a 16-million-square-kilometer (6.2-million-square-mile) belt that extends through the Sahara Desert in northern Africa, across the Arabian Peninsula, and into northwest India. But when conditions are right (or perhaps ‘wrong’ would be the better word), swarms invade countries on all sides of the recession area, as far north as Spain and Russia and as far east as India and southwest Asia. As many as 60 countries can be affected. Swarms regularly cross the Red Sea between Africa and the Arabian Peninsula and are even reported to have crossed the Atlantic Ocean from Africa to the Caribbean. Monitoring locust habitat during recessions means monitoring a large, forbidding expanse of arid and semi-arid terrain, often in conflict-ridden, developing countries with little infrastructure or technology.

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Normally, desert locusts live relatively solitary lives in the arid central Sahara, Arabia, and Persian Gulf regions (green). When conditions are right, however, they form swarms that migrate for thousands of kilometers (yellow). It is these migrating swarms that form plagues. (Map adapted from The Desert Locust in Africa and Western Asia: Complexities of War, Politics, Perilous Terrain, and Development, by Allan Showler)