• Choose a category
• All
• Classic-Fiction

By Root 618 0

its kitchen dregs, made for an interesting cafeteria experiment) among the subs suggested that they were indefatigable scavengers. Moreover, whenever they came upon live prey, even frail ones, they were ungainly in making the kill. The half-dead flies I slapped from my neck managed to crawl to freedom, with only one or two workers clinging ineffectually to them for a time. The subs were more successful when their numbers were greater: one healthy fly made the mistake of landing on a busy column of workers and was captured—an example of a trail serving by chance as a “trap.” The subs were also different from other army ants in that they seldom slung food, whether a rice grain or an insect, under their bodies. Instead, groups of up to six carried food between them by grabbing it at different angles in the manner of other species of ants. Perhaps the standard army ant protocol didn’t work well in the confined underground spaces where they normally foraged.

The real surprise was that the species didn’t seem to forage in a mass, at least not with the quick and cohesive advance of the trailblazers of other army ant groups, such as Stefanie’s tightly packed laevigatus. This had to be the reason the subs were ineffective at catching prey. Rather, the workers would slowly—over a couple of hours—spread apart from a hole in the ground or one of their trails until they had scattered across an expanse 30 centimeters or more from where they had started. As they searched during the ensuing hours, some went as far as 10 centimeters from their neighbors—a long way, relative to their size and leisurely movements. Mind-numbing to document, this activity didn’t involve a raid front or any other kind of regular progression.

The workers had no trouble, however, coordinating food harvesting. A strong column of them developed quickly after I dropped a dead cricket in front of a lone ant. But this behavior looked more like what I would expect from run-of-the-mill ants than from army ants, which recruit to food items during the advance of a tight raid. The pattern can be difficult to pick out from all the action, but to see recruitment in a swarming species like rubellus, it’s best to find a worker that has accidentally become separated from her neighbors, perhaps among the stragglers from a raid or on patrol near a trail after a disturbance. Drop an insect in front of this ant, and she runs in loops, releasing pheromones that set nearby ants to looping in the same manner until they converge on the prey.19 In a rush, a column of ants extends to the quarry, and they carve it apart.20 By strewing dead insects in the washbasin, singly or in numbers, I found not only that the sub recruited help far less explosively than her army ant relations, but that she wasn’t doing so during the advance of a raid.

The army ant “sub” species at the field station in Gashaka, Nigeria, would forage for kitchen refuse, such as this pebble slick with cooking oil that they are carrying.

If the Nigerian subs hadn’t belonged to one of the army ant subfamilies, I wouldn’t have given them a second glance. After all, many ants have foraging patterns in which many independent workers “diffuse” outward from trails or nest entrances, laying recruitment trails when they find new food.

That thought brought to mind Pheidologeton affinis, a similarly unprepossessing and partially subterranean ant that I’d studied a few years earlier at the Gombak Field Station in peninsular Malaysia.21 I had hoped to detect raids in affinis, since it is cousin to the marauder ant, my Pheidologeton diversus. At Gombak, in a low building in a clearing in a forest, I lived on instant noodles cooked in a room with no electricity. Bats swooped by my kerosene lamp each night as I wrote my notes. My clothes, washed in a bucket out back, never dried completely, which gave everything I owned a mildewed odor. One week, the kitchen tap yielded only a trickle of foultasting water. A brief investigation netted me the corpse of a snake that had plugged the pipe to the rooftop cistern. Feeling queasy, I sat