Locusts and Grasshoppers | Things to Know

East Africa is in the midst of an alarming desert locust outbreak, which has caused serious damage to farmland in Kenya, Somalia and Ethiopia. Triggered by factors such as weather and agricultural practices, once-solitary insects can become social creatures, forming swarms millions strong. The end result can be devastating for crops, often in economically precarious areas. And climate change could just make the problem worse. Check out our video for insight into what makes a locust a locust, and how an insect can go from minor player to major pest, seemingly in the blink of an eye.

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Editor’s note: This video, originally published January 16, erroneously included some images of katydids. The video has been updated to correct the species of insects shown and to include new footage of the current desert locust outbreak in East Africa.

Transcript

In late July, Las Vegas got an influx of unwanted visitors. Millions of pallid-winged grasshoppers took Sin City by swarm. For a few weeks, the insect cloud was so big it could be spotted on radar. But were they grasshoppers or were they locusts? And what’s the difference between the two? It’s a simple question, but it doesn’t have a simple answer.

All locusts are grasshoppers, but not all grasshoppers are locusts. Grasshoppers are solitary creatures, out hopping between blades of grass. Locusts are a small handful of grasshopper species when they enter a swarming phase. When a series of factors — which can vary by geographic area, weather and species — force grasshoppers to crowd each other, their serotonin levels rise, and they begin to swarm. This behavior is referred to as gregariousness. It’s a rapid onset of social behavior.

When it comes to identifying locusts versus grasshoppers, scientists say it all comes down to how they behave. What incites gregariousness varies by species. For example, touch. Locusts brushing against each other is often a trigger. But what causes crowding? Usually weather. In the 1990s, droughts and low humidity in Indonesia spurred a locust breeding frenzy. But in China and Central Asia, a period of flooding that leads into a dry period can create the right conditions for locusts to mate. Other outbreaks, like in Australia, might be triggered when the rain falls during locust breeding.

Whatever the causes, the effect is the same: as many as 31 million locusts per square mile and swarms as big as 460 square miles. And they’re taking a toll. There are thousands of species of locusts and grasshoppers. At least 500 are known to cause crop damage and 50 are considered major pests. Kenya is in the midst of a desert locust outbreak, which has already caused serious damage to farmland in Somalia and Ethiopia — and the insects are still on the move. And we are only making the problem worse. Deforestation, invasive species and overgrazing on fragile grasslands are helping locust populations. Climate change will likely make conditions even more favorable for swarms.