Let me inject a little horror into your morning coffee.
You are hiking on a mountain in Tanzania, enjoying the view of its shadow spreading purple over the savannah. In the dry stream bed crossing your trail, you notice what appears to be dark water moving below. Odd, you think. Odder yet, it is flowing uphill. Not quickly — barely 20 yards an hour. You clamber down the stream bed to investigate, and find that the dark water is a river of voracious ants crawling beside and over each other, the broad head of the column filling the entire gulch. You watch a grasshopper disappear into this throbbing swarm, smothered in ants until not even a bulge exists where it once stood. I can outrun these, you think — and turning to do so, you stumble on a rock and twist your ankle. You crawl uphill, clawing at the loose dirt for handholds, but soon you feel the weight of the ants grip your calves like hands. Moments later, your entire body is burning as the ants’ powerful mandibles, sharp as scissors, shear your skin, then your fat, then your flesh. Every millimeter of your body is being devoured. But don’t worry; you will die long before they chew all the way to your heart. You’ll asphyxiate first as the ants enter your every orifice, invading both your esophagus and your lungs and choking off the air supply to your nose and throat with the sheer multitude of their hungry bodies. You will never know that the meat of you will be carved into pieces and hauled back to the nest to feed the queen and her writhing grubs.
This, or something like it, is what happened to some unlucky bastard in 2006, and what happens to a few unlucky Africans every year at the jaws of the siafu, or driver ants. Since the head of a hunting swarm’s column is rarely more than 60 feet across and slow-moving, most people are able to avoid it. But if you are asleep, or drunk, or an abandoned infant, or very old or sick, you may fall prey to the gluttonous siafu. It is said that even elephants flee from a marching swarm. For much of the year, the siafu hunt and gather food in all directions, like most ants. But in the dry season, when food is scarce, they change their tactics. They gather in columnar swarms of up to 50 million workers, march in a new direction, and, like Sherman’s armies, destroy every living thing in their path. Moving slowly as they do, it can still take 4 hours for the carnivorous parade to pass by. That they are born without eyes is no handicap; they navigate by smell and feel, and by following their sisters.
Such a destructive lifestyle makes the siafu necessarily a nomadic species. They rarely bother building nests in the ground. Instead, they build ingenious structures called bivouacs, constructed from living members of the the colony. The queen and her young are protected beneath a domed nest made of interlocked legs and arms, and can safely move through the plains or forests within. The siafu makes a home out of itself: a living, writhing home of jaws and stingers.
Another odd aspect of their nomadic culture is what it’s made of the males. Breeding male siafu are known as “sausage flies,” and look almost nothing like their sisters; they were once thought of as another species altogether. Fat and winged, they are the largest of all ants. They leave the living nest once hatched, and if they survive into their lonely adulthood, they must wait to reconnect with their own species. Once they smell the pheromone trail of a traveling swarm, they fly closer to investigate. When the swarm recognizes the male, they rip his wings off and carry him back to their queen to impregnate her. The life of the male siafu is that of a fat, ugly-duckling sex slave.
What fascinates me about the siafu, and their New World counterparts the army ants, is that they function more like a natural disaster than a predator. Like a forest fire, they destroy anything too slow, sick, young, or old to get out of their way; no exceptions, no mercy. They are a biological carpet bomb. They are not just an organism; they are an event. And like many natural things, they could be called an act of God… if you’re the sort who believes in God, and believes that He often has to be devastatingly cruel to be kind. Because like anything that emulates fire, the siafu do fire’s work of cleansing the forest of pests and disease and slowness, ultimately promoting a healthier ecosystem. No species, whether insect or mammal, suffers more than another, but all eventually benefit. The siafu keep the forest clean, and evolution on its toes.
That said, enjoy this nightmare-inducing clip from The Hellstrom Chronicles, the most bad-ass insect documentary ever made. If you dare.