Appeal for rapid response and anticipatory action
Locusts are the oldest migratory pest in the world. They differ from ordinary grasshoppers in their ability to change behaviour (gregarize) and form swarms that can migrate over large distances.
Among locusts, the desert locust (Schistocerca gregaria) is the most destructive in the world. It has a significant impact on food security, trade and the economies of many countries throughout the world. In response to environmental stimuli, dense and highly mobile desert locust swarms can form. Desert locust fly during the day downwind for up to 150 km in a day. Meanwhile, hopper bands can march about 1.5 km per day.
They are ravenous eaters who consume their own weight per day, targeting food crops and forage. A swarm measuring just a single square kilometre can contain up to 80 million adults, with the capacity to consume the same amount of food in one day as 35 000 people. Large swarms pose a major threat to food security and rural livelihoods.
During quiet periods (known as recessions) desert locusts are usually restricted to the semi-arid and arid deserts of Africa, the Near East and Southwest Asia that receive less than 200 mm of rain annually. This is an area of about 16 million square kilometres, consisting of about 30 countries.
There can be an exponential increase in locust numbers with every generation of breeding: a 20-fold increase in their numbers aer three months, 400 times aer six months, and 8 000 times aer nine months.
In 1954–1955, Morocco lost over USD 50 million (in 1994 dollars) to desert locust in six weeks in the Souss-Massa Valley alone.
In 1958, Ethiopia lost 167 000 tonnes of grain, enough to feed a million people for a year.
Locusts are becoming even more dangerous in the context of exceptional weather events associated with climate change, due to their very high capacity to take advantage of new situations. This is illustrated by the fact that the locust situation has deteriorated with recurrent droughts since the beginning of the twenty-first century.