most other ants in that they have no fixed home. They spend their time
either on the move, hunting for insects, spiders, and the occasional small
lizard, or camped out in temporary “bivouacs.” (Eciton burchellii
“bivouacs” are made up of the ants themselves, arrayed around the queen
in a vicious, stinging ball.) Army ants are famously voracious; a colony on
the march can consume thirty thousand prey—mostly the larvae of other
insects—per day. But in their very rapacity, they support a host of other
species. There’s a whole class of birds known as obligate ant-followers.
These are almost always found around ant swarms, eating insects the ants
have flushed out of the leaf litter. Other birds are opportunistic ant-
followers and peck around the ants when, by chance, they encounter
them. After the ant-following birds trail a variety of other creatures that
are also experts at “doing exactly what they do.” There are butterflies
that feed on the birds’ droppings and parasitic flies that deposit their
young on startled crickets and cockroaches. Several species of mites hitch
rides aboard the ants themselves; one species fastens itself to the ants’
legs, another to its mandibles. A pair of American naturalists, Carl and
Marian Rettenmeyer, who spent more than half a century studying Eciton
burchellii, came up with a list of more than three hundred species that live
in association with the ants.
An army ant from the species Eciton burchellii .
Cohn-Haft didn’t hear any birds and it was getting late, so we headed