http://www.fao.org/3/a-i4353e.pdf
The Desert Locust (Schistocerca gregaria) is considered the most dangerous of all migratory pest species in the world. It threatens people’s livelihoods, food security, the environment and economic development. It can easily affect more than 65 of the world’s poorest countries. It can reproduce rapidly, migrate long distances and devastate crops and pasture. The Desert Locust has the ability to change its behaviour and appearance, under particular environmental conditions (unusually heavy rains), and transform itself from a harmless individual to part of a collective mass of insects that form a swarm, which can cross continents and seas, and quickly destroy a farmer’s field and his entire livelihood in a single morning.
A Desert Locust adult can consume roughly its own weight in fresh food per day that is about two grams every day. A 1 km² size swarm contains about 40 million locusts, which eat the same amount of food in one day as about 35,000 people, 20 camels or 6 elephants.