Credit: Daniel Goldman, Daria Monaenkova

Fire ants adjust their digging behaviour when building underground nests, depending on the size and dampness of the material they are working with.

Daniel Goldman and his colleagues at the Georgia Institute of Technology in Atlanta studied fire ants (Solenopsis invicta; pictured) as they constructed tunnel networks in silica particles designed to mimic soil of varying moisture levels and particle size. Using X-ray imaging, the team found that up to a point, ants dug deeper tunnels through clay-like and fine-grained particles as the moisture content increased, using the growing stickiness of the particles. When digging, the ants either carried individual grains away if they were large, or gathered and compressed smaller particles into a pellet.

The authors say that this adaptability could help to explain how this species has successfully colonized large parts of North America.

J. Exp. Biol. 218, 1295–1305 (2015)