Acromyrmex versicolor (leafcutter ant) pictures

Here are some Arizona Acromyrmex versicolor (leafcutter ant) pictures.  The nests of these ants do not look the same as the Atta leafcutter ants of the tropical rainforests. Rather than being large mounds covered with leaf fragments, Acromyrmex nests tend to be small volcano shaped gravel cones. Also, rather than only cutting living leaves (as the Atta), the Acromyrmex I've seen are quite willing to cut dead vegetation - dried grass, dead leaves, seed coatings, seemingly any vegetation.

Acromyrmex versicolor is quite common in some areas of the Sonoran Desert.  They may not be easy to find, though, if there has been a prolonged dry spell - they stop being active and allow their nest mounds to blow away.  Within a couple of days of good, soaking rains they will reappear (assuming they survived!) and begin building their nest mounds again. They are especially prevalent in and around sandy washes after rains.

A few movies (AVI format) of leafcutters in action:

Click on the thumbnails for larger versions of the pictures.

The nest mounds are usually volcano shaped and distinctive. There is often more than one mound is in an area - I don't know if all of the mounds go to one nest.

When they forage, the leafcutters form columns from the nest to their foraging area, as in this photo

Side view of one of the nest mounds.

Acromyrmex in profile. Note the spines on the thorax.

Close up photo of head in profile. The ant has droplets of water on her - it had been raining on this particular day.

Frontal view of head. If you look near the tip of her right mandible (jaw), you can see what looks like a mite. These mites live on ants.

Here is a leafcutter cutting a stem. You can see the notch that she has cut.

The leafcutters will chew on stems until the stems fall. Often the ant will fall to the ground with the stem.

Once on the ground, ants continue to chew the stem until the fragments are small enough to carry.

There are several castes within the colony. Here is a minor worker, or minim, between two major workers.

Carrying a stem back to the nest

Several leafcutter workers attacking a Pogonomyrmex rugosus (Rough Harvester Ant) that wandered into the nest mound

Working on the nest mound

Acromyrmex and Euryopis (the Spider)