If people, viewed from a great height, look like ants, do ants, viewed at close range, look like people? Of course not. Ants have six legs, compound eyes, no lungs, and impossibly narrow waists, and they tend to hang around with aphids and mealybugs. Still, behavioral similarities make them excellent analogues. Ants, like humans, are into career specialization, livestock herding, engineering, climate control, in-flight sex, and war; for them, as for us, free will may or may not be an illusion. As for whether ants look to humans for insight into themselves, science has no answer.
A few years ago, Marko Pecarevic, a Croatian graduate student studying conservation biology at Columbia University, met with his adviser, the urban ecologist James Danoff-Burg, to come up with a subject for his master’s thesis. Danoff-Burg had some data on ants in city parks and wondered if Pecarevic wanted to work on that. Pecarevic thought not. But afterward, crossing Broadway, he saw ants crawling around a garbage bin on one of the avenue’s medians. Medians! As habitats, the planted medians of Broadway were ubiquitous but overlooked, suitably biodiverse but extraordinarily distressed. For someone interested, as Pecarevic was, in the ecology of heavily compromised urban environments, medians were like remote, unexplored island chains—a Galápagos in Manhattan. He decided to be their Darwin. Employing Google Earth (forgive him, he’s from Zagreb), he chose three median-rich stretches—Park Avenue, the West Side Highway, and Broadway—then made himself an official-looking ID, dressed in parkish green, and started collecting ants, travelling the city with a duffelbag of garden tools and Evian bottles filled with antifreeze. No one bothered him.
On a recent afternoon, Pecarevic, a trim, wry thirty-two-year-old, went out on a survey of his medians. For demonstration purposes, he had cadged a plastic cup from a coffeeshop, and pocketed a spoon. He carried, as he always does, an aspirator, a plastic tube that he uses to collect ants. He inhales them, alive, into a chamber. “Sometimes, when you suck up ants, they’re not happy about it,” he said. “If you blow cigarette smoke on them, they calm down.” Really, this was a farewell tour—he was returning to Zagreb the next day, to pursue a doc-torate. His thesis (“Ant Diversity and Abundance Increase with Increasing Plant Complexity and Amount of Garbage Bins in New York City Street Medians”) was done, and he was bequeathing to New York some interesting conclusions about its ants.
For example, ants seem to have an astute sense of neighborhood stereotypes. The Upper West Side, as it happens, is more diverse, ant-wise, than the Upper East Side. Diversity is a function of habitat, and habitat, on the medians, is reflective of the people who live around them. As you might expect, Park Avenue medians contain fewer gar-bage cans (the greatest determinants of ant variety and abundance) and less complex flora; they are more manicured, less riotous. “On some parts of Broadway, it doesn’t look like anyone’s been there for years,” Pecarevic said. Ants like that.
Pecarevic surmised that ants got from one median to another mostly via intercourse. A queen and a male, both winged, mate in the air—the nuptial flight, as it’s known. The male dies, and the female, alighting in a new place, starts a colony. One mating session provides her with enough ant sperm to last a lifetime; she can produce an egg every few seconds for the rest of her life. (This arrangement holds on both sides of Central Park, so we should infer nothing about the connubial difficulties of 10021 versus those of 10024.)
To collect the ants, Pecarevic had also laid pitfall traps, three per median. These were clear plastic cups dug into the dirt, and partly filled with antifreeze. The ants fell in and died quickly, before they could dismember one another. He left the traps for three days. To warn off maintenance crews, he had affixed tiny signs to toothpicks, which he stuck in the ground. After emptying the traps, he spent three minutes around each one, sucking up live ants with the aspirator. Back home, he poured the antifreeze through a colander, over the toilet. He washed and preserved the ants in alcohol. Over the course of two years, he had collected six thousand six hundred and nineteen ants, from forty-four medians, and identified fourteen species.
There are roughly twelve thousand known species of ant. The three most common, on the medians, were, in ascending order, the cornfield ant, the thief ant, and, from Europe, the pavement ant. “If you see an ant walking on pavement, it’s probably a pavement ant,” Pecarevic said. Also, if you see ants fighting on the pavement. “They have huge fights. They bite each other.”
The day was hot and hazy—maybe not so good for anting. On the median at Seventy-fourth Street, on Broadway, Pecarevic turned up spoonfuls of earth and sifted through them, as though digging for steamers. Nothing. Ants: never there when you need them. On Seventy-sixth Street, he found a colony of pavement ants in some rotting wood bordering a flower bed. They ran wild over a Popsicle stick, a plastic spoon, pistachio nuts, Marlboro butts, and degraded credit-card receipts. No fighting and biting today. On Park Avenue, south of Seventy-ninth, he prowled a begonia bed and a bit of parched lawn, under some cherry trees. Antless.
Two summers ago, on Broadway, north of 100th Street, Pecarevic discovered a species that had previously never been found north of Virginia, the Chinese needle ant, an invasive predator with a powerful sting. He’d found four of them—a colony, perhaps. He went back again last summer, but the needle ants were gone. He theorized that the cold winter had wiped them out. “I was hoping to find more,” he said. “It would have been nice to get some funding for more research.” There will be ants in Zagreb. ♦