Every several years, parts of Africa are likely to be covered by a dark cloud, a living cloud made of billions of locusts that are travelling across the continent eating everything in their path.
Plague of Locusts
  Plague of locusts is a worldwide disaster of biological agriculture. There are nearly 100 countries or regions have been attacked by it. Especially in Asia and Africa.
  The drought makes the locusts largely reproduce in a very short time because they like the warm and dry weather. ...