Excerpts from Jim Conrad's
Naturalist Newsletter

from the January 16, 2005 Newsletter written at Hacienda Komchen de Los Pájaros just outside Dzemul, Yucatán, MÉXICO
ARMY ANTS
The other morning I was weeding the lettuce when gradually it dawned on me that over to my right the ground was moving. It was an advancing front of army ants and I didn't have much choice other than to turn the lettuce patch over to them.

Unlike the leafcutter ants I told you about earlier, which can carry away every bit of leaf and flower material in a tree or garden, army ants are carnivorous, not vegetarian, so my lettuce was safe. As the ant-front advanced I watched as worker ants fastidiously searched beneath every lettuce leaf, in every crevice in the ground, and around the corner of every stem. Any small animal that couldn't get away was doomed. I've read that army ants can dismember and devour animals as large as goats, but the largest thing I've ever seen them tear apart was a grasshopper. And you should see the grasshoppers springing from the grass as a wave of ants moves through it.

The site at http://www.insecta-inspecta.com/ants/army/ {now offline} says that when army ants rest, or "bivouac," they form tunnel- and chamber-containing nests from nothing but their own bodies. They do this by fastening onto one another with their mandibles (jaws) and claws. The site also says that army ants, though possessing simple eyes, are blind.

The blindness doesn't seem to hinder them at all. In fact, as you witness their amazing degree of organization and cooperation, it's easy to believe that they may have senses, or experience a sophisticated manner of being, we humans can't even imagine. You might be interested in reading about the idea that ant colonies may possess a "collective intelligence" at http://www.knowledge.co.uk/frontiers/sf066/sf066b07.htm {now offline}.

The first-mentioned website also claims that army ants work at night. I have often seen them working during the day, as on my lettuce-weeding day. That site is focusing on just one species. A site on New World Army Ants at http://www.armyants.org/indexfiles/speciesindex.html {now offline} lists 45 army-ant species in Costa Rica and we probably have that many or more here in Mexico.

Once I spent a summer living next to a family in the Nahuatl-speaking country of eastern San Luis Potosí, in east-central Mexico. That family by no means suffered Alfred Hitchcock moments when army ants invaded their house. In fact, they seemed to rather like it.

First, it meant that they could abandon the day's chores, go sit in the park, and if someone asked them why they were being so lazy in the middle of the day they could just say "ants" and everyone would understand.

Second, army ants do a great job cleaning houses of scorpions.