Adventures Among Ants - Mark W. Moffett [38]
Like most ant species, the marauder ant is a central-place forager, meaning its food supplies are funneled to a single central nest, which houses the queen and her brood. It is here that the society invests most heavily in defense, which makes excavating a marauder ant nest excruciating for scientist and insect alike.
But I had to do it. Studying marauder ants without looking in a nest would make as much sense as studying people without looking in a house. I also knew the ants well enough not to take my first attempt at snooping into their home lightly. Thinking the whole business out in advance, I selected my combat gear: long pants, a long-sleeved T-shirt, a pair of tightly woven socks, and tough boots. Arriving at the Singapore Botanic Gardens, I tucked the shirt into my pants and the pants into my socks and advanced toward the nest with a sharp-tipped shovel. Hovering over the nest, I breathed deeply for a moment before slamming the shovel into the earth. I had loosened a tiny chunk of nest soil; immediately a mass of enraged ants poured from the entrances. I threw the soil to the side and dug in again. And again. It took only a few tossed scoops before workers of all sizes had swarmed over my shoes and socks and up my pants and shirt to the first exposed skin they could reach: my neck and wrists.
When I could no longer tolerate the hundreds of bites, I ran to where I was out of range of the nest and scraped the ants off my skin and clothing. Then I grabbed the shovel anew and leapt back into the fray.
Repeating this cycle a few times, I found that the horde of minor workers pouring from the expanding gash in the soil had moved out many meters. Adding to the problem, the ants knocked off my body had spread out to the safe havens I’d used previously. Eventually, I had to sprint away from the nest to find a moment’s respite from the desperate defenders.
The thrill of a dig is in locating the queen. A marauder queen is a good runner, and during the time it takes to excavate a nest she’s likely to have been on the move, which makes it hard to know where she normally resides. On my first excavation, she was cloaked by an entourage of workers of all sizes and as a result—ouch!—a pain to catch.
It is yet another example of the value of media and major workers that battles between their colonies are fought only by the minor workers, while the larger ants—the heavy artillery—enter full combat mode only at the most desperate hour: when the nest is threatened. This distinction makes military sense. In 1914, the British engineer and military theorist Frederick Lanchester proved the advantage of outnumbering the enemy, even using troops of inferior quality, when battles are fought in large-scale formations. Hence, the minor workers, which per capita require little in the way of resources for a colony to rear and maintain, form a kind of “disposable caste” for both combat and predation. During colony conflicts, fights are one on one, making for a battle of attrition in which quantity trumps quality.10
After witnessing an excavation, Paddy Murphy claimed to be in awe of my tolerance for marauder bites. However, the payoff was a delight: I got an inside look at the marauder’s home life. Their nests are often at the base of a tree, where the colony takes over available hollows such as abandoned rodent burrows, cavities left when a root decays, or even buried jars—any space in the earth will do. Suspended among the heaps of workers in these hollows are eggs, larvae, pupae, and victuals such as seeds and legless animal bodies. Also present are smaller, outlying chambers dug by the ants themselves, an activity that results in telltale piles of soil around the tree base. These are near, but typically separate from, the ants’ midden piles of seed husks and discarded insect parts.
In the outlying chambers are the pale callows, adult ants so young their exoskeletons haven’t fully hardened. Here, the young minor workers take on the role of nurses, tending the brood. Also crammed in these chambers are major and media repletes—a special