Scientists have identified a chemical compound released by locusts that causes them to swarm, opening the door to possible new ways to prevent these insects from devouring crops vital to human sustenance as they have for millennia. Researchers said on Wednesday they identified the pheromone - a chemical produced by an animal that affects the behavior of others of its own species - in the world's most widespread locust species, the migratory locust, or Locusta migratoria. Called 4-vinylanisole (4VA), it is primarily released from the hind legs and is detected by the antennae of other locusts and sensed by odorant receptors, the researchers said. Swarms can include billions of locusts and span hundreds of square miles (km) as the insects voraciously consume crops, imperiling food security. Migratory locusts inhabit Asia, Africa, Australia and New Zealand, attacking pastures and critical crops such as wheat, rice, corn, millet, barley, oats, sugarcane and sorghum.