As recently as 1963, plagues of ravenous desert locusts could stretch across continents, blanketing lands from West Africa to India up to 14 years at a time. Today, with pesticides and early eradication efforts, such biblical swarms no longer occur. But as farmers in Sudan, Egypt, Israel and Saudi Arabia can currently attest, locust swarms remain a serious regional threat.

Locusts are grasshoppers that have evolved to undergo a sort of Jekyll-to-Hyde transformation, a result of sporadic patterns of rainfall.

After a particularly wet season, deserts bloom into life. Vegetation supports a growing population of thriving grasshoppers. When the rains cease, the leaves wither and the hungry insects begin congregating in the last patches of remaining plant life.

As the grasshoppers crowd together, something shifts. The insects, which normally live alone, begin bumping into one another. When grasshoppers touch one another’s hind legs, the contact sets off hormonal changes: The adults’ neutral brown coloring is replaced with a fearsome bright yellow, and they become “gregarious” group insects, coordinating their growth, behavior and egg laying. When the swarm devours all of the surrounding vegetation, it takes to the air, traveling up to 100 miles a day in search of its next meal.