These Swarming Locusts Are Grasshoppers Gone Wrong

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They might look like harmless grasshoppers, but locusts have an appetite for destruction. When the conditions are right, they transform from mild-mannered loners into gregarious partiers. They swarm, causing chaos and suffering at the level of a biblical plague. So what sets them off?


This might look like a harmless grasshopper, but under the right conditions it has an explosive dark side.

It's a locust, with an appetite for destruction that can rise to the level of a biblical plague.

All locusts are grasshoppers.

But the only grasshoppers we call locusts are the ones that swarm.


Most of the time, locusts are mild-mannered.

They stay put, and blend in to avoid predators.

This is their solitary phase.

Locusts can live like this for generations.

Until something sets them off.

In the arid regions across the world where locusts make their homes, that trigger is often a hard rain, especially following a drought.

That deluge makes plants flourish.

The solitary locusts eat and eat, fueling up and making more locusts.

As their numbers swell, they inadvertently bump into each other.

The hairs on their back legs are particularly sensitive.

And that contact triggers a pulse of serotonin: a hormone that transforms them from loners into partiers.

In just a few hours they can go from a solitarious phase to a gregarious phase.

Molt by molt, the locusts change from a camouflage green to an in-your-face yellow and black.

The bright colors help scare off predators by telling them the locusts taste bad.

These transformed locusts have a huge appetite, and not just for food.

Pretty soon they’re surrounded by baby locusts.

That’s when things start getting crowded.

Even a feast this big won’t last long with so many hungry guests.

The restless young locusts start hopping and marching together, forming groups called bands.

It’s a locust outbreak.

As the locusts mature, they grow wings and take to the air.

The giant swarms number in the billions.

They devour entire farms in hours, wiping out people’s livelihoods, and causing mass starvation and misery.

Outbreaks like these can last for months or years, even decades.

It takes huge amounts of insecticides to knock back a full-on swarm.

A better strategy is to catch minor outbreaks before they get massive, but they can be hard to spot.

Researchers at Arizona State University are looking into one way to defend against locust destruction by making land less inviting to some species.

They put locusts into wind tunnels to see how far the insects can fly based on what they eat.

They’ve found some locusts thrive, and spread farthest, on a diet rich in carbohydrates.

Land managers can make their crops and pasturelands richer in protein and lower in carbohydrates if they increase the amount of organic matter in the soil.

Avoiding overgrazing helps, too.

Those are expensive propositions and currently out of reach for many.

But if we can keep working on ways to cut back on the carbs it might just help prevent a plague

Hi, Deep Peeps

For this episode, we collaborated with PBS Monstrum and their host Dr. Emily Zarka who came out to film with us.

Hi, Emily!

Tell us about the show.

Hi, Laura!

PBS Monstrum takes a closer look at monsters, myths and legends. Our new episode is all about giant locusts and the "Big Bug" subgenre of science fiction and horror films from the 1950s.

I look at how anxieties about atomic energy, pesticides, and communism show up in these giant monster bug films.

See you there!


The Global Locust Initiative: