Why do ants sometimes congregate above ground in a huge writhing red mass? I looked at one of these ant-masses up close this morning and I couldn’t figure out what they were doing. There were a lot ant corpses that the survivors seemed to be moving around, but other than that, they didn’t seem to be getting much done.
leave the ants alone. look at humans more closely.
I’ve seen this too. It seems to be some kind of ant cotillion. If you look close, the ants are in face-to-face pairs or sometimes menage a trois. There’s little movement, only of ants still seeking partners. I’m fascinated, and bewildered. One of these days I must read up on it.
If you also listen, rather than just look… I mean listen real closely… you can hear music. They are doing the hokey-pokey. 
Actually, it could be that the ants are fighting. Sometimes when ants from other mounds try to crash the party, a fight will ensue. I don’t know if they will fight same species ants from other mounds, or just other species ants from other mounds. Did all of the ants involved look the same?
…that’s what it’s all about <clap><clap>
yes, they all looked the same.
I see this all the time in the spring, though.
I thought that maybe they were fighting, but they were moving so slow!
I found that you can blow on them and THAT’S when they start to scatter about and move fast.
That only lasts a few seconds, though.
Then they go back to whatever they were doing.
I didn’t hear the Hokey-Pokey…
They sounded more like a rave.
A RAVE?!? Damn these young ants today. Why, back in my day…
Usually when I see a mass of ants like that, they’ve found a big hunk of food, like a dead worm or something. Maybe they’re all there for a big feast, or maybe they’re cutting up the food into little pieces to take back home with them. Anyway, that’s just my WAG.
No, there wasn’t any hunk of food.
It was just ANTS!
A million of them- some of them were pairing off, there were a lot of dead ants that were being ignored, then there were some dead ants that were being carried off- I don’t know where though.
The more I think about this, the more aggravating this is becoming.
I went out an hour ago to see if they were still there, but some dolt had poured water all over the spot.
Some one must have asked this question before!
And someone must know the real answer!
PLeeeze help me.
D’y’all think Cecil would know?
He’s been ignoring me on this.
Here’s a new idea. I know it won’t ultimately help that much since it’s a WAG, but here goes…
Perhaps the ball of ants was triggered by some sort of “panic” chemical given off by one of the ants. Some ant species will bunch up in a ball like that (although on a much larger scale) when they are in water. They probably do it more from “Where the heck is high land?!?! Hey (stepping on Fred), now I’m a little more out of the water. Cool, I’ll just stay here.” than anything else, but perhaps there is actually a chemical transmitter that causes them to do this. Maybe this chemical got triggered in one or two of the ants somehow, causing a small ball to form.
Did I mention that that was a WAG? Perhaps I should qualify that, and call it an extreme WAG. 
I have seen the ants quit their underground habitat en masse when it’s been flooded. That might be what you saw.
Also, don’t ant colonies sometimes migrate? I know some species, like the carpenter ant, swarm (like bees), but I thought that an ant colony might also sometimes pick up and move somewhere else.
Oops! Still not used to the new board. I repeated what Steve-O had said immediately before me. :o
Okay, this is going to be really obvious to some readers, but nobody above has specifically pointed it out, so I think it’s worth mentioning for those readers who are WAGging but missing something important.
[obvious hat ON]
I can tell you what they’re not doing: They’re not mating. Assuming you’re looking at drones and soldiers, they’re female/sterile. Only the queen ant mates, during population cycles in which winged males are produced. (This is a simplification.)
[obvious hat OFF]
I apologize to those of you for whom that was already self-evident. But like I said, I figured it was worth mentioning.
Anyway, I did a fair amount of ant research a while back for a screenplay I wrote – I read the entire Holldobler/Wilson “Ants” cover-to-cover, for example: jump back and touch me! – and although I’m not a myrmecologist, my own thoughts follow.
Various ant species have all sorts of different behaviors. It’s impossible to generalize from a simple “a bunch of ants are doing such-and-so,” because the varieties are so different. You could be looking at a bivouac, if the ant species is a legionary type (are you in Texas?). It could be a battle, as previously observed, possibly in a colony that’s trying to split off with separate queens but that hasn’t quite gotten the geographic distance yet. Something could have happened to the nest, say an invasion or flooding, and the clump could be ants grouping together to stay warm, or removing corpses from the lower reaches of the nest burrows.
Can you tell what kind of ants they are? What color? How big? Size differential between worker and soldier? Recessed fossa? How many segments in the antennal club? Are the tarsae rugulose?
Okay, fine, I’m kidding a little. But you get the point, I hope. Until we know what species of ant you’re looking at, anything we say is going to be, by definition, a Wild Ass Guess.
I’m sure that what you are seeing is an ant war, even if they are moving slowly. Is it cold or early morning at the time you are observing them? That would account for their slowness. The pairing off, the dead bodies, no food, all add up.
To make sure, you might get out a magnifying glass and check them out for evidence of ant grenades, ant-omic bombs, prisoner of war camps, etc. . . . just kidding.
I’m with the ‘bivouac’ explanation. Some ant species exist as mobile colonies, with no set living quarters. When they’re on the move, they tend to be fairly spread out, but when at rest or in a ‘panic and protect’ situation, the grunts form a protective mass around the queen.
If you’re feeling adventurous, you might try seeing if there’s a queen in the middle of the mass, but be aware that, one, you might destroy the colony, and two, ants get very very violent when protecting the queen.
And if they’re fire ants, don’t get within a hundred yards.