Swarms: The Science Behind Biblical Locust Plagues

Subscribe if you love science, chaos, and bugs that are way too confident.

In this Swarms Minisode, Katy dives into the desert locust, a grasshopper that transforms—literally—into one of the most devastating swarm creatures on Earth.

🦗 What causes a peaceful insect to go full apocalypse mode?
 🌾 How do they morph from shy loners to yellow, muscle-bound sky-hulks?
 🌪 What triggers a swarm so massive it consumes everything in its path—eating its body weight daily?
 📈 And why can’t we stop them, even with modern tech?

From serotonin surges to plague-level salad destruction, this episode unpacks the shocking science behind locust swarms, how they form, what fuels them, and why the only thing that can stop them is literally nature itself.

🎧 This is episode 3 of our 6-part Swarms series—bite-sized, bizarre, and biologically unhinged. We know we had two mini episodes in a row, that was not intended, but sometimes life just gets in the way of our fun!

Transcript

Katy: [00:00:00] this episode of Wildly Curious, we're gonna be talking about another mini episode of Swarms and I'm gonna be talking about desert locusts in particular.

Just because,

and I learned 

Laura: Plague baby. Plague it 

Katy: yeah. yeah. Might as well Give me a solid Plague.

here, guys. Alright. So again, the, this, the desert locust in particular, they're one of the ones that I've known to cause the huge, huge, locust swarms, and so like of apocalyptic,

On wings kind of thing. So we're gonna be talking about one of the most devastating, chaotic and scientifically just crazy swarms on the planet. The desert locust or oc circa gregia.

Laura: Okay. 

Katy: we'll 

Laura: Gregarious, , I'm sure, meet. Well, if you're gregarious, you like to hang out with people.

Katy: Correct, correct. And so that's gonna come into play here in a second. So these, this desert locust in particular, they have two modes. Regular old grasshopper just minding their own business. [00:01:00] Or biblical plague like

it is one, one or one or the other. And they can

switch back and forth. 

Laura: I can respect that. I, I, I don't want anyone to describe me that way, but I'm slightly envious of being like, man, she's just totally normal and then plague level 

Katy: wait, wait until you hear why I didn't know, the details of all this stuff. So just, just

Laura: Okay.

Katy: that thought 'cause it actually gets funnier. I understand grasshoppers now. I never thought I would understand a grasshopper. I can empathize with them. So like I said, the particular ones that we're talking about is the desert locust, the, and it's a species of shorthorn grasshopper found across Africa, the Middle East, and parts of Asia.

Laura: Okay.

Katy: Now here's the the twist. Taxonomically speaking. A locust is a grasshopper. The word locust isn't a separate species or anything like that. It's more of a behavioral label, let's just

say. So it. 

Laura: uh, like vermin?

Katy: [00:02:00] Yes, yes. So it refers to any, there's several of the short horned grasshoppers that can form swarms. So there's only certain of these grasshoppers that can actually form swarms and this, and this is one of them. But the environmental conditions have to be just right. So that ability to swarm has evolved independently and at least 18 Jane across five subfamilies of grasshoppers.

Laura: 'cause they do in the United States too, 

Katy: Yeah. Oh Yeah.

Yep. So again, locus is the term. Locus is less of a family name and more of a warning label

I 

Laura: Yeah, yeah, yeah. 

Katy: So most of the time the desert locust lives a quiet life.

Like I said, it's solitary, shy hops around, eat, leaves, minds. Its business for the most part. It's an introvert just does its thing. But when the environment changes, for example, when a long drought ends and rains return and the plants start [00:03:00] blooming, the population just explodes. And with too many grasshoppers and too little space, that's whenever they start to actually transform. And this isn't just a okay, I guess I'll hang out with other insects now swarm. No, this is like when that biblical plague

switches here. And this , from its name. You've mentioned the gregarious phase. This is whenever it switches. So what triggers it touch specifically physical contact with hind legs? So as everything's, so

let's say you have a 

Laura: is like when you're at the, this is like when you're at the grocery store and somebody hits your ankles.

Katy: Basically, yes. But

Laura: Oh, you're right. I totally understand going 

Katy: Right, right, right. So think of it this way. You go through a drought and then all of a sudden the rains come, they get all excited. That causes them to start mating like crazy.

And then the population booms and the more

physical contact with their hin and legs, multiple, multiple, [00:04:00] multiple times per minute, over several hours. That kind of constant bumping leads to the surge in their nervous system, which releases a hyper amount of serotonin.

so this. 

Laura: still feel good. So they like it that this is 

Katy: Not necessarily.

But then whenever it starts to spike, that sets off a physical transformation. The color changes that they have, it goes from green to, there goes the thumbs up again. So I can't, I have

to count with my pointer fingers. Now the, the color changes from green or tan to a bright yellow with black markings.

This is the desert Lucas in particular muscles. They start bulking, bulking up and getting str what is happening? Why are there balloons everywhere now? Oh my

gosh. 

Laura: said bulking up and they were like balloons. 

Katy: Balloons. What? Ha I don't even know. But it, this never happens to you. This only

ever happens to me. Anyway,

so muscle. 

Laura: I know you're confused, but it's just [00:05:00] weird stuff happening on 

Katy: Yeah. And, and yeah, and squad cast, and I don't, I have no idea what's happening. Muscles, they start bulking up and getting stronger. Their wings, everything starts to get, the brain starts to rewire for activity, movement, group attraction, all this kind of stuff.

So that surge in serotonin,

Laura: They just hulk out.

Katy: yak it, it literally is a hulk. So they don't just tolerate each other, they start to actively seek each other out. So swarming becomes not just possible, but necessary because it's almost like their nervous system is like, you know, what would make this a lot better? A a billion of us is

essentially what they say. so eventually it gets to a tipping point where there's too many of 'em, they've bumped into each other too many times. They're like, you know what, at, at first this was fun. Now I'm, I'm over it. And then that's whenever they are like, just, ah, and they just lose it

Laura: And eat everything in sight. Think of the munchies afterwards. Drugs are bad Kids. 

Katy: Yeah. Right? Yeah. Right. Serotonin good. But clearly in large quantities, it'll make

you hulk out and then [00:06:00] swarm and

then, and then want to touch 

Laura: in sight.

Katy: Right. I have too much. No.

Um, yeah. Right. So they can travel up to 90 miles or 150 kilometers in a single

day, riding the wind in basically just a massive swarm cloud that can stretch up to a for a thousand square kilometers.

All right. In some cases, they have estimated up to average 80 million locusts per square mile, or that'd be 270 ish locusts in a,

in A half mile. Is it a half? Yeah. Half mile.

'cause a square kilometer is about a half a mile, so the

largest swarm ever recorded. 

Laura: over you.

Katy: Right. You, you can't, as, you can't

Laura: I mean, that's what the plague of Egypt was. Literally these locusts, because they live in the same place and for sure you would think that this was the end of the world really though. It was just [00:07:00] some hopped up.

Katy: yes.

Yeah. 

Laura: hopped up grasshoppers just feeling good baby running through Egypt.

Katy: So

the

largest swarm ever recorded, not estimated recorded, was not this desert locust, but it was called Albert's Swarm. And it was happened here in the US and it comprised of Rocky Mountain Locust, which is now an extinct species. But this swarm was estimated to be made upwards of 12 trillion

individuals. 

Laura: that would just like it would, they would eat everything and your family would starve to death. Yep. 

Katy: Yep. So how much do they eat? Speaking of that, each one eats its own body weight and plants daily. And when

you do the math across millions and millions or billions or trillions, that's a salad apocalypse right there. Like you

Laura: Solid. Solid apocalypse. Especially if you're named something like the desert Locust. Probably not already. A lot of plants there to even eat.

Katy: No. Right, so, so you're gonna move. So you're gonna move and you're

gonna devour whatever you [00:08:00] can

find. 

Laura: everything in sight, which means everything. Every other herbivore in the area just dies

Katy: So just like the Starling, whenever they're in that swarm, it's, they still maintain those, , the same three rules is what a starling does. Stay close but not too close. Match the speed and direction of your neighbor and just follow the crowd. And that's how they end up moving

around.

And again, the end result ends up being a massive shape shifting wave and it just gets to be, be insane.

Laura: I like grasshoppers, but nobody likes 

Katy: that many Right, 

Laura: those spiky legs and they just be like, biffing you in the head like cicadas do. 

Katy: right. No.

way. So researchers though have used drone tracking software. The un has a whole 'cause of course, the food, what was it? FOA food and something agricultural lines. Like they track whenever

these happen. Yeah, because, because it

is so, yeah. 

Devastating. 

Laura: jeez.

Katy: Because why does this all matter? So again, let's, I said some numbers earlier.

So let's [00:09:00] just put this into perspective here. So 80 million locusts into just one square kilometer. It's about 200. Sorry, I said earlier, I said 270, about just over 200. So about 207 million per square mile locust, which is insanity. And , any plant that they come across, they eat

because they have to, they have to eat their own body weight every day. Here's the scary part, 'cause I never really thought about this until now. A locust swarm doesn't just stop whenever it's full or tired because it's never going to be full or

tired. 

Laura: day they get hungry.

Katy: So it only stops when food runs out. The weather, there goes a thumbs up again. The, the, when the food runs

out,

weather changes. , And more rain comes and it like breaks 'em up. So

Laura: break it up, break it 

Katy: yeah. So that's the only thing. It has to be a force of nature. You, because you can't chemical spray them with anything. People have tried be like, oh, let's just douse them with a [00:10:00] tongue. No, they live and they keep, they breed and they move and theyre, and so it just, you can't stop this thing. So unless there is an actual force of nature that makes them stop, you can't stop it. It just

continues to go. So yeah. So I didn't get, because it's a mini set, I get, didn't get too

into the weeds with all this stuff. . So anyway,

so you guys desert locust,

Laura: That's nuts. I never wanna see that. Never

Katy: never. Never. Your sharks starlings. I've seen That's cool. The shark swarm that you talked about.

That's cool. Locust. No thanks. No, thanks. All right guys, we'll make you on that note. Make sure you go check us out on Patreon and then follow us on our social media channel's, wildly curious podcast. And then yeah, go support us on Patreon. And until next week

Laura: Bye.