Swarms: Why Army Ants Are the Forest’s Most Ruthless Hunters

Subscribe and prepare yourself—because this time, the swarm doesn’t just chase... it devours.

In this Swarms Minisode, Katy Reiss and Laura Fawks Lapole dive into the world of army ants, some of the most strategic, aggressive, and terrifyingly coordinated hunters on Earth. From building living bridges to raiding the forest floor with military precision, these ants don't forage… they sweep, and anything that can’t move fast enough is gone.

🐜 Why army ants don’t build nests—but become one
 🚨 How their raids dismember prey in minutes
 🧭 Why they create living bridges and run two-lane traffic systems
 🌪 And how other species follow their swarms for leftovers (like antbirds!)

This is more than an ant episode—it’s a masterclass in swarm strategy, evolutionary teamwork, and why being organized is deadly.

🎧 This is episode 5 of our Swarms series—quick, chaotic, and scientifically intense.

Transcript

Katy: [00:00:00] we're gonna continue another mini episode for swarms. And this week I'm talking about one that, again, this fits the category of, I guess I never really thought of it being a swarm, but it is. And we're gonna be talking about army ants.

Laura: Ooh, yes.

Katy: This, this was a, this was

Laura: I actually saw them 

Katy: pretty cool one.

Oh, have you? Oh Yeah.

'cause you were down in Costa Rica

Laura: Yeah, it was wild. Wild.

Katy: yes. So when I say army ants, quote unquote, it's very similar to the locust. If you listen to two episodes ago, when I talk about the locust, locust is just a broad label for grasshoppers. Whenever they start to swarm army ants. We're not talking about one species.

It's actually a whole group. More than 200 species spread across the Americas, Africa and Asia.

But today in particular, we're gonna focus on the queen group of coordinated chaos. Is Ian Belli? I don't know, but it's the [00:01:00] classic army ant of Central and South America. This is the one that has been studied, the one that is talked about. So if people are like, oh yeah, it's an army ant and it's in Central South America. This is, this is this one. So these army ants are mostly blind. These ones are not all ants are. Most ants do have compound eyes, but these army ants are mostly bind nomadic and absolutely restless. But they're organized

Laura: They got that Z route.

Katy: Right.

No. Yeah. Right. Migratory restlessness so they don't build nest and trees or dig tunnels underground. Instead, they create a temporary home called a vivo bi, B-I-V-O-U-A-C-S.

Laura: Oh, well I know what a, a bvo whack is like a 

Katy: Biac. There we go. Wait, bvo

Laura: but then Bvo whack us.

Katy: BI don't know. Anyway, these [00:02:00] are temporary homes that are made entirely of themselves.

Laura: so freaking cool. Just

Katy: Thousands of ants will lock their legs together.

So again, opposite of the grasshopper, locust that I talked about, where it's like, yeah, they like the touch for a little bit and then they're like, get the

heck away from me. Yeah.

And then they just, ants, they lock their legs together to form a, literally a living, breathing fortress that protects the queen and the rest of the brood.

So it's an organic home with. Mandibles

Laura: Can you imagine like finding that and just like touching it and it just like,

Katy: right. So, and these ants don't just randomly swarm. 'cause they do swarm, and I'll get to that in a second. They have a schedule, like they do it by a schedule. 'cause again, remember ants are very strategic, like very strategic, very methodical, very

Laura: Yeah. There's like no wasted.

Katy: No, none at all. So army ants cycle between two phases. A station, I can't do a thumbs up, A stationary [00:03:00] phase where the colony just chills in one spot while the queen lays the eggs.

Pepe, develop all that stuff. Then the second phase is the nomadic phase, and that's where things start to get crazy. During the nomadic phase, the colony moves every single night and RA and does raids. They literally call it raids daily, covering new ground constantly, and never raiding the same area twice.

So 

Laura: like eat everything there.

Katy: everything. So a single colony of ants can contain hundreds of thousands of individuals. Estimates can range from 200,000 to 600,000 ants, just on average,

but it's not the size that makes 'em terrifying per se. It's the tactics that they use. Again, I said raids. It's coordinated ant raids, which that alone just sounds terrifying, but think of it as like they sweep across the forest floor like a [00:04:00] predatory blanket.

They move, they fan in and out. Anything in their path that

can't move fast enough is gone. Insects gone, spiders gone. Even small vertebrates like frogs, lizards, baby birds, if the timing's wrong, gone. So anything that's like gets caught. They're swarmed.

Dismembered, and 

Laura: mob. 

Katy: Yeah, and they're 

Laura: just like

Katy: Yep. It

just takes 'em over.

And so they're dismembered and then they're carried off piece by piece in a matter of minutes. So it's literally

like, 

Laura: so cool.

Katy: So, and it's so, it's not just like a hunt, it's a straight up takeover of that area.

And they don't stop to eat. They're always on the clock, always moving, bringing back food to the group in waves, just constantly.

Laura: I will never forget when I saw it. Well, first we heard it, we were 

Katy: yes, you hear 'em. Yes. Which is [00:05:00] nuts. 

Laura: Yeah, because it's ants, right? But all of a sudden you hear 

Katy: I'm, I'm gonna use that sound bite right there for, I don't know what, but something because it's

ants 

Laura: ants

Katy: lines.

Laura: because like, you don't 

Katy: You don't expect ants to make 

Laura: like here and foot drive. John, like, what are you not expect to hear ants tiptoeing through the forest? Like it's tiny little ant, but it was like, like rustling. And yes, some was not the ants because ant birds 

Katy: Oh, I'm gonna talk about that in a second. So don't, yeah, don't give

that away. 

Laura: So that, but then, then they started to come up with a path.

And the people in charge of the, of the walk were like, Hey, you gotta move your boots. Do not let them in your boots because they'll just go in your boot and start biting you. So like we just had to move out of the way. And it wasn't that they were trying to like specifically target 

Katy: yeah, yeah, 

Laura: sure that they know that we're far too large and it's a waste of energy. But they went around and our leaders were like, boy, I sure hope they make it back to camp where we were because we, they were [00:06:00] like, because after that then we don't have to worry about the cockroaches and the scorpions and the spiders anymore because they eat them all.

Katy: They eat them all. Yeah. So how do they swarm? Army ants pull off a raid that looks more like a flood, like we just talked about than like the one by one foraging trips that you're used to seeing. Ants, they move in a coordinated column, guided not by sight, but by smell. So just like we talked about with Laura's last one, it's all on pheromone trails. So basically chemical breadcrumbs that are laid down by each other, and that's what paints them. Like the picture of, Hey, where we should go. When an ant finds food, just like what Laura talked about with the bees, it lays down extra pheromones on the return path, intensifying the trails that they all know where to go. More ants followed, more pheromone builds, and suddenly the colony is a high speed speed. Prey pipeline. Their raids spread out in a fan shape, like I said, like a ground level search party just [00:07:00] sweeping the forest floor. They surge through leaf litter up trees around roots, flushing out insects, spiders, and even small vertebrates.

Laura: I just can't imagine how scary it would be to be something that size 

Katy: And seeing 

Laura: or, I mean, you are much larger. Let's say you're something like as large as 

Katy: a mouse or a frog. 

Laura: but you hear, and you know what's gonna happen to you if you don't 

Katy: right? Yes, yes. You've seen your friends being torn apart and dismembered,

Laura: dismembered?

But by the tiniest little mouth 

Katy: right. Uh, 

Laura: death.

Katy: So that is how they normally, normally these army ants, this is the norm, all right? It is like the leaf they eat through, they lay down the pheromone chairs, that's fine. If it's in its nomadic fade, they, it's just amplified. And so they never raid the same area twice. They will avoid places that have been rated by e even other colonies of the same species. So they're very strategic scent [00:08:00] based cartographers. They're

basically making 

Laura: wanna waste your time going someplace where there's no food.

Katy: e Exactly. And it's very coordinated because they run like two lane traffic system outbound ants yield to inbound ants carrying food because when your literal whole colony is dependent on a tight schedule, like efficiency matters. If there's a hole or there's a dip, the individual ants, and this is also what they're very well known for, the individual ants will measure themselves and if they fit, they'll just lie down across the gap, like a living bridge and just let others go

over if it's, yeah, if it's too big, the other ant checks and then they will go ahead and kind of link together just like they do in their little home to make their home.

But they'll plug holes to keep pre LA and supplies lines moving fast. They do whatever they can to keep that food. If let's say like that column or whatever is going out, they find food and then the ans like lay that pheromone track coming back. 'cause again, they're mostly blind.

So they [00:09:00] lay that pheromone come trail coming back and then they find like a whole dip.

They're like, oh my God, we gotta get this food back. Like at all costs. We have to make sure that these other ants get back. So they do whatever they have to make sure they come back. . So here's the other really cool thing about them, and I can kind of end with this. So, army ants just aren't good at hunting. They're better than, for the most part, everything else in the forest, because again, it's not, a, stalking, it's a swarming. So they flush out and they capture prey that most

Predators. never even notice.

So there's plenty of insects, there's plenty of prey there. Tiny insects that hide in the soil under leaves, inside bark. They sweep. They don't stalk. They sweep, and while they're tearing through the undergrowth, the forest isn't just watching like the forest itself's reacting. So other animals like beetles, birds, and lizards will actually follow this swarm

picking off prey that's fleeing the ants. There are even bird species, like ant birds that have evolved to rely [00:10:00] on army ant raids as their primary hunting strategy. No ants, no dinner. So the ants they eat what they catch, the birds eat. Then what escapes the ants,

Laura: Yeah.

Katy: which is just a full, full blown like food chain on the move,

move kind of thing. 

Laura: Smart evolution. 

Katy: No, no, it, 

Laura: only depend on that, but.

Katy: yeah. Right. So anyway, yeah, so that's army ants. And again, it's like I knew about them. I knew about the cool thing, like the building the bridges and kind of stuff like that, but I had no idea and I only touched on a bit of what I actually went through and researched it. But

how organized, how precise,

but then like how just unstoppable and very much so like the grasshoppers, for the most part, it doesn't stop until it something.

You know? Again, it's like the locust, some, some

outside force has to really stop them to be able to, to stop 'em. It's not just a, it's not, they just get tired and

they're Like okay guys, that's 

Laura: [00:11:00] fire or 

Katy: Yeah, no, they have to, it has to be an outside force stopping them. So anyway, so that's Army hands guys.

Laura: So cool. I didn't know everything about them either.

Katy: Yeah. All right guys, so next week we'll have another full length episode, and then the week after that we will have our last mini so on swarms. So make sure you guys go check us out and support us on Patreon. If you can follow us on all, all of our social media channels, just search the Wildly Curious Podcast, and until next week.

Laura: Later.