Bala bites of passage
By Natha Welton
Natural History Magazine
October 2002

Costa Rica’s La Selva Field Station is a gathering place for tropical biology’s most brilliant minds. Its research facilities, with easy access to the jungle, harbor lethal snakes, wild pigs, snapping turtles – and mad scientists. The scientists happily spend their days plucking the wings off aerial insects and crucifying them on Styrofoam boards, others molding poison dart frogs out of Play-Doh, or shooting climbing ropes into the forest canopy with crossbows. I arrived at the station with little understanding of what compelled this scientific tribe to seek increasingly peculiar forms of academic exercise.

I’d come to La Selva to work with the bala ant (Paraponera clavata), also known as the bullet ant. These insects are inch-long behemoths whose stings feel like gunshots. One finds them on trees throughout the jungle, effortlessly toting the body parts of recently dismembered victims – grasshopper heads, frog legs, beetle thoraxes – into large black holes in the ground.

Whether or not the primitive balas used castes to accomplish their grim work was a mystery my colleagues and I wanted to solve, and our mark-and-recapture methodology required us to handle the beasts. Our plan was to collect arboreal foragers and nest-tender; compare body lengths, head sizes, and weights; and then paint foragers one color and the nest-tenders another. If afterwards we consistently spotted, say, green ants in the trees and red ants on the ground, we would have found a caste.

To collect the balas, I invented a masterful piece of equipment I called the Cryogenic Ant Sucker, which, theoretically, would chill the manic ants to a manageable speed. By gluing two rubber hoses to the cap of a small flask filled with crushed ice, I could create a vacuum in the one tube by inhaling on the other. Thus equipped, I ran through the forest sucking up thousands of unsuspecting, benign leaf-cutter ants -- convincing myself that the contraption was uniquely suited to the task.

Then I tried to collect the balas.

The ants were so big (or so smart) that they could brace themselves against the edges of the collection tube by stretching out their appendages. The Cryogenic Ant Sucker was unfortunately doomed. Instead, my comrades and I resorted to inserting a long stick deep into the bala nests and thrashing it madly. When the furious ants charged up the stick, we’d smack it smartly against the top edge of an ice-filled chest, and the ants would drop inside. After they were chilled, we’d paint their motionless bodies psychedelic colors and release them back into the forest.

Early each morning for several weeks we ventured into the jungle to our nest-thrashing and ant-painting, but the ants caught on to us. They began to cling to the stick, refusing to drop into the chest. Only at the stick’s rebound did they release their tenacious grips, which made them into dangerous missiles. Inevitably, one of my colleagues fell victim to an ant sting that confined him to bed with an ice pack, immobile, for thirty-six hours. A few days later, another colleague succumbed to the same fate.

One evening toward the end of our study, we began antagonizing a new nest and couldn’t figure out why no ants were emerging. Then some ants darted out a back exit at my feet, and soon a moving blanket of black was crawling up my socks. By furiously jumping up and, I dislodged all but one, which made its way to my knee, clearly heading up my shorts. Panicked, I tried to flatten it with our D-cell flashlight, completely missing my mark but successfully battering my shin. Although I eventually knocked the ant off, my leg swelled horrendously, and I realized I might just as well have let the ant have its way with me. Still, in my misery, I was consoled: This was my initiation; I had joined the scientific tribe.