What do trap-jaw ant nests look like?

Ants are accomplished architects, but most people would never know it. That’s because ant nests are often underground and impossible to observe directly, with the consequence that we don’t know as much about ant-built structures as we do about those of the more open-nesting bees and wasps.

Nest casts of Odontomachus brunneus

Enter Walter Tschinkel. Walt and his students have perfected the art of pouring casting materials into ant nests, waiting for the slurry to harden, and digging up the resulting structures. The various chambers and passageways are transformed into sculpture, and what was invisible is cast openly in three dimensions. It’s a great trick, and the Tschinkel lab has churned out a string of papers on ant nest engineering.

The latest paper, a survey of nest shapes in the trap-jaw ant Odontomachus brunneus, was led by Lina Cerquera and came out last month in the Journal of Insect Science.

Odontomachus brunneus

Odontomachus is a predatory ant with small colonies, so one might not expect their nests to be overly complex. And it turns out that’s the case. These trap-jaw ants construct a single vertical shaft with chambers dug out to the side, and the overall volume of the nest is proportional to the number of ants in the colony. From the paper (emphasis mine):

No matter what their size, the nests of O. brunneus can be recognized by their characteristic appearance; that is, the size-free shape does not change much with nest size… [This] means that workers need only follow simple, local iterative rules to produce a nest of similar shape but any size.

This finding is in line with previous work on insect architecture, where complex structures emerge through the aggregate action of many individuals following a small set of behavioral rules. Nothing surprising, but isn’t it a luxury just to have the means to see underground?

Source: Cerquera LM, Tschinkel WR. 2010. The nest architecture of the ant Odontomachus brunneus. Journal of Insect Science 10:64.

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5 thoughts on “What do trap-jaw ant nests look like?”

  1. That is really, really, REALLY cool. Kudos to the Tschinkel lab for developing this technique and allowing us a peek below ground…

  2. I saw a documentary several years ago on a similar process. They used concrete on a grass cutter ant nest. It was massive! Seeing the complexity and size really gave me a new appreciation for what they can accomplish. Looking at these results, it’s cool to extrapolate how small yet consistent designs accumulated to create the grass cutter superstructure.

  3. Charcarodon Megalodon

    Not all Odontomachus nests are small. Here in Mobile I’ve seen enormous nests that seem quite complicated. They surround the bases of trees, with multiple entrances that are spread along the above ground roots. I’ve done some investigations, and each tree seems to have one colony, rather than multiple colonies clustered together. The species is either brunneus or haematodos. It’s quite fascinating.

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