Adventures Among Ants - Mark W. Moffett [102]
A mature Amazon nest houses five thousand ants, comprising both the slavemaker workers and their more numerous slaves. Inside the nest, the slaves tend the stolen pupae until they transform into adults. Like hatchling birds that imprint on their parents, a young ant quickly learns to recognize the individuals around her and thereafter treat them as family. This imprinting is based on the scent of other pismires, an archaic term for an ant that derives from a colony’s pungent odor. Whenever ants meet, they sweep their antennae over each other to confirm the presence of the blend of compounds that identifies their nestmates.3 If the odor matches expectations, they treat each other as sisters-in-arms. If an individual smells wrong, the workers will either run away from each other or fight.
In most ant species, this imprinting is infallible, because the youngsters are surrounded by sisters in the nest of their mother, the queen. But when slaves-to-be mature in an Amazon nest, they imprint on their captors. Assimilated into the wrong society, the ants are duped into a life of servitude, doing all the drudge work their masters won’t: building nests, foraging for prey, harvesting honeydew, slaying free-living Formica that enter their territory, and taking care of the brood. The Amazon slavers’ only job is to go on raids, replenishing the store of Formica pupae as their enslaved workers age and die.
The slavemakers do so little for themselves that when I pulled a sandwich from my backpack and dropped a bit of turkey in front of an Amazon worker, she walked right past it. Incapable even of recognizing a meal, she is unable to feed herself. Eventually one of the slaves found the stash of poultry and retrieved it to the nest.
At once more brawny than a slave and yet as helpless as a baby, the Amazon worker gets her sustenance only after her servants find food and, like birds with their nestlings, regurgitate it to her. She can neither excavate tunnels nor raise the queen’s young. She is a fighting machine, nothing more. The curved daggers she bears as jaws are useless for any chore except assaulting free-living Formica, but they deliver the ultimate in all-purpose tools: a new stash of slaves. Even with their superior armaments, though, the Amazons are so outnumbered they would be massacred if it weren’t for a chemical known as a propaganda substance that they wield as a social weapon, released from a gland associated with their mandibles, which throws the bombarded colony into mayhem and flight.4
Ant slaves harvesting a dead grasshopper as one of their Amazon “masters” walks by in the foreground. The Amazon ants would starve if their slaves didn’t feed them.
The tolerance of Formica argentea to frequent raids is a sign that this species shares a long history with Polyergus breviceps.5 After countless generations of attack and counterattack at Sagehen Creek, the Formica have apparently come to treat their losses as a cost of doing business. “Resistance is futile,” declared the species-enslaving Star Trek creatures known as the Borg, who make decisions collectively, like ants.
LIFE IN A NUTSHELL
A year later, far from California, I found myself studying a second, unrelated species of slavemaker ant—Protomognathus americanus—in the hope of experiencing some of the variety of ant slavemaking behavior. For the second day in a row, I stooped over the little Protomognathus ants, trying not to disturb the action. One of the dark-pigmented slavemakers had been about to find an acorn housing a nest of Temnothorax when two Temnothorax workers managed to sting the slightly larger ant to death. That had been the last of several close calls for the free-living Temnothorax, two of which lay nearby, killed in earlier confrontations. Another hour crept by, as my arms cramped under the weight of the camera, before a slavemaker with better luck found her way into the acorn through a split in its side. Dozens of the Temnothorax within immediately fled, each grabbing