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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