The Horror of the Slaver Ant
Everything changed when the slaver Nation attacked. What used to be a thriving colony is now a captured country. Slaves do the work, serving their new Masters until they die, only to be replaced by new victims harvested in brutal raids. But let's go back to the beginning.
The world war of the ants is raging, claiming millions of lives every day. But in the brutal world of ants, straight-up war is not the only way. Around 50 ant species practice slavery, the most extreme division of labor. We don't know how this began, but some ant species perfected this cruel trade.
Meet Polyergus, the most intense of the slaver ant tribes. There are different species, but generally, they're 4 to 10 mm long with brown to blackish bodies and sickle-shaped mandibles. Polyergus has specialized in slavery so much that they've lost their ability to care for themselves. They don't clean, build nests, care for their brood, or feed themselves; they only exist for raiding. Slaves make up 82-90% of the ants in their colonies, so a few hundred Polyergus and a single queen control thousands of slave ants.
We'll summarize and simplify what we know about Polyergus into one grand story. You can find more information in our sources. So now, let's witness the cruel banality of nature: The Raid. It all begins on a mild summer morning on a sunny field. Witness this colony of over 10,000 Formica ants, genetically cousins of Polyergus, who build a thriving nest underground. They are a widespread genus; some species are good fighters, some great builders, and some cattle farmers, often welcomed by humans because they hunt vermin that hurt forests.
Nobody noticed the lone Polyergus scout that briefly showed up this morning before she bolted away again. The attack begins in the early afternoon. The scout returns from her mission to find the Formica nests. She dances erratically and spreads pheromones that excite and mass recruit more and more ants until a large raiding party of a thousand warriors has formed. A close-packed, well-organized column up to 10 m long begins to move.
As the Polyergus raiding party arrives at the Formica colony, the attack begins almost immediately. Dozens of attackers begin digging and clearing debris from the nest entrance to make it easier to storm. As soon as they're done, hundreds of the attackers rush inside. The defenders vastly outnumber their attackers and are formidable warriors able to shoot acid. But instead of fighting back effectively, they seem confused and scatter.
Rather than fighting back, Polyergus also seems to be somewhat resistant to the acid sprays of the defenders, and so even if a defense is forming, the attackers use their mandibles to pierce and kill. There are a few different ideas as to why Polyergus attacks are so efficient, and one of the most fascinating ones is chemical warfare. Instead of relying on brute force, they release a propaganda pheromone that makes the defenders panic, unable to mount an organized defense.
The attackers have nothing to gain from intense and costly combat other than immense casualties. What's more, they actually want their victims to survive so that they can be raided again in a few weeks. As the raid unfolds, the attackers breach deep into the colony, looking for their most valuable possession: the colony babies. They grab the pupae and larvae that will make up the next generation of Formica and carry them out of the nest. Hundreds are abducted and brought back to the Polyergus colony in this raid alone. While most of them survive, a few unlucky ones are eaten as a sort of snack.
The surviving victims will be turned into slaves. After about an hour, the raid is over, and the Formica can begin to recover. It seems their only strategy is to make even more ants. A decent-sized colony can forfeit thousands of pupae in a single raiding season and still survive. Although in this case, while the raid was going on, something even more sinister happened.
Hold that thought, though, because how are Polyergus turning ants into slaves? How to brainwash ant slaves? Ants conquered almost the entire planet over 100 million years ago. They owe their success to being social animals that perfected chemical communication. Chemical signals and cues let ants know what their colony needs and what each individual should do, and most importantly in this case, who is a friend or foe.
Slavemaking ants are much less social than other ant species. Some species miss a lot of the genes other ants have to make communication possible. In a sense, they are bad at talking to each other. So it may be that as Polyergus ancestors started to abduct other ants, they lost the ability to collaborate and work together productively. Soon after the stolen Formica offspring have been brought to the slaver colony, they are progressively covered in Polyergus pheromones. They are chemically imprinted, similar to a duckling who imprints on a mother after birth.
When the new slaves hatch, they behave as though they are part of the Polyergus colony and begin to work for them unconditionally—keeping the nest clean, caring for the next generation of slaves and masters, hunting for food, and feeding their enslavers mouth-to-mouth. This sort of brainwashing goes so far that if they encounter free Formica ants in the world, they will treat them as enemies. In a sense, they're not true slaves, as they serve willingly and show no interest in freedom. It's more like violent abduction and adoption, which doesn't make things that much better.
As the Formica only live for a few months, a constant new supply of victims is necessary to survive. Polyergus can never stop enslaving. How to make new slave colonies? How are new Polyergus colonies created? After all, Polyergus workers are so useless that a queen can't start a new colony without slaves. But how does she make slaves without warriors?
It turns out there are two main strategies. The more dangerous one might unfold during a raid, like the one we witnessed before. A young Polyergus queen silently follows the raiding party. Using the chaos of the invasion, she's able to find her way to the Formica queen and kill her, taking over the shaken colony. Although such a victory may be very short-lived, Polyergus do not tolerate other slaver colonies within their hunting ground. They raid each other fiercely too and can destroy the competing colonies nearby. So, while this tactic sometimes works, it is pretty dangerous.
Another young queen is going for a different strategy. She's looking for a Formica colony that is further from her birthplace. Attacking a whole colony on her own, she bolts through an entrance, pushing aside confused ants that try to stop her, releasing a powerful appeasement pheromone that drives defenders away. She has only a short time window to find the Formica queen deep in the hostile nest. Once she finds her target, both queens engage in a fight to the death. The Polyergus queen is well equipped; with her sharp mandibles, she bites and rips into her victim for about half an hour before she finally calms down.
Between her bites, she licks the chemical surface of the dead Formica queen, covering herself in her pheromones. When she's done with this macabre ritual, Formica workers approach her, subdued by her intense smells. They start grooming and feeding her as though pledging their allegiance to their new ruler. She still might not be done, though; Formica colonies often have multiple queens, all of whom need to be defeated, which is not guaranteed. Often, attacking queens will be stopped by a balance of workers that rip her apart or are defeated in a royal battle.
But if she does manage to kill all the queens, the colony has been taken over, and the enslaved brood will begin to serve a new queen, the usurper. She now begins laying eggs that are cared for by her new slaves until new Polyergus ants hatch that will soon start new raids on neighboring colonies.
No matter what we humans do, quietly below our feet, the world war of the ants is raging with wild and horrible strategies fought by billions of individuals every single day. Polyergus will continue to hunt for slaves, as to stop raiding would be their demise. And in the war of the ants, there is no giving up.