Ants from a Kilometer Up

So you like insects, but can’t be bothered to get up from your computer to go look for some? Google earth to the rescue!

South of Tucson, Arizona (31°38.097’N 111°03.797’W) I found this lovely aerial image. Visualized from an elevation of about a kilometer and a half, it shows a hill just west of I-19 covered in freshly-sprouted grass. Except, there’s this strange pattern of evenly-spaced polka-dots:

What could account for the speckles? Alien crop-circles? Bizarre gardening accidents?

Why no, those are the nest discs of one of our most conspicuous insects in the Sonoran desert, the red harvester ant Pogonomyrmex barbatus. Down on the ground it is harder to get a sense of the even spacing of the nests, but the discs are plenty obvious. The ants keep the large area around their nest entrance free of vegetation and other unwanted debris. Below is a photo I took south of the Huachuca mountains, not far from the google earth image above:

Even closer-up, here are the engineers:

North American Pogonomyrmex aren’t the only ants whose engineering prowess is visible from low-earth orbit. Some of the more spectacular leafcutter ants in South America make even larger mounds. The image below the fold is also from Google Earth, 1 km over the Paraguayan Chaco (24°06.914’S 57°22.240’W).

The little green speckles are Copernicia palm trees, but what are the white pimples?

They are ant nests, of course! The chaco leafcutter Atta vollenweideri makes earthen mounds several meters wide to house the million-plus ants in the colony. Up close mounds look like so (with a pair of Peace Corps volunteers thrown in for scale):

Here’s the critter responsible:

I’m pretty sure these aren’t the only cases where insect activity can be seen in Google Earth. I’d bet there are places where Australian meat ant nests might show up, or African termite mounds. Plenty of opportunity for the deskbound entomologist to go hunting!