The first Atta we saw were the captive colonies at SASI. These were my first views of Atta. I was familiar with the leaf cutters (Trachymyrmex) we have around Las Cruces and elsewhere in the Chihuahuan Desert, but these were very different ants. While the Trachymyrmex were seemingly slow and deliberate, almost catatonic in their movements, the Atta were more like the stereotypical ant, moving rapidly and with purpose to their movements.

The first ants we saw were near an arroyo west of the visitor center. The mounds produced by these ants were the largest I’d ever seen at nearly 2 meters in diameter. The excavated soil was a rich red-brown color and stood out from the surrounding soil surface. There was an interesting odor permeating the air that was the result, we were told, of byproducts of the fungus garden refuse. The Atta minors were about 1 cm in length and impressively spiny. The majors were every myrmecophile’s dream. Some were just over 2 cm in length, aggressive and powerful. We spent most of the afternoon examining these nests and following the foraging trails that radiated out nearly 100m in some cases. These foraging trails ran just below the surface for most of their length with an occasional opening marked by a small cone of soil. The ants radiated out from these openings searching for appropriate forage plants to use as a substrate for growing their fungus gardens. One of the more interesting choices of plant from my perspective was creosotebush (Larrea tridentata).

As the afternoon progressed toward evening the temperatures began to drop. At one point, we were all putting on warmer clothing and commenting on the falling temperatures. The ants continued to forage until around 5:00. At this point, activity began to drop off at an increasing rate until there was only an occasional ant moving along the trail. We took this as an indication that we should get camp set up and decide what to do about feeding ourselves.

The following morning dawned cool and cloudy. We had a leisurely breakfast punctuated by an interesting self-cooking package brought by Ken Kingsley (I think it was Ken, if not, my apologies to whomever it was that like some adventure with their meals). This package had a string that was pulled; thereby mixing some set of chemicals that produced a noticeable swelling and steaming of the package, not unlike some cases of volcanic activity I’ve seen on TV.

Once the morning festivities were finished, we headed to Senita Basin to look at another set of Atta nests. The scenery in the basin is always spectacular. I’ve been here several times, but I was never aware of the presence of Atta. This area of the monument is even more special knowing this ant is here. One of the nests we saw was amazing. The mound must have been nearly 5 m in its longest dimension. We found a trail of ants carrying ocotillo leaves. It was easy to follow the trail back to the ocotillo that was the target of this group of ants. A stream of ants was in constant motion to and from the plant. Leaves were falling in a steady stream, some of them carrying an attached ant. It was easy to see how these ants could defoliate a medium to large shrub in one or two days.

Some of the other creatures of interest we encountered were a couple of Vaejovid scorpions, a small Scolopendra, and a carpet of tiny (1-2mm) blooming plants that later were identified as an Eriogonum species by a friend in the New Mexico Native Plant Society. There were also the usual ants, Pogonomyrmex, Phiedole, Aphaenogaster, Myrmecosystus and several others. For anyone with an interest in ants, this trip, which I understand to be an annual event, is well worth attending.