Scientists say they’ve discovered a chemical pheromone which causes locusts to swarm.

The insects, which are able to eat their own weight in a day, can wreak havoc on crops when gathered in vast groups.

In recent months, swarms have devastated crops in dozens of countries including Ethiopia and Kenya.

Researchers say the locusts emit a perfume-like scent when close to others of their kind.

This fragrance draws in other locusts, who in turn also begin emitting the scent, causing a loop which results in enormous swarms.

Scientists hope that this discovery will allow the problem to be tackled by genetically engineering insects without scent receptors or using the pheromone to attract and trap the pests