Scientists in Brazil have uncovered the full extent of a massive underground nest built by leaf-cutter ants after filling it with ten tons of cement and excavating the hardened cast. The structure, belonging to the species Atta laevigata, spans 500 square feet and extends 8 meters (26 feet) below the surface in the Cerrado region, housing what was once a colony of millions.

The cement cast revealed a highly organized network of tunnels and chambers, including oval-shaped fungus gardens for food cultivation, designated waste areas, and ventilation shafts designed to facilitate airflow. Researchers found the ants had moved approximately 40 tons of soil to construct the nest, with tunnels engineered to withstand overburden pressure and prevent collapse.

Analysis of the cast, published in the Brazilian Journal of Biology and other journals, shows the nest utilized natural convection currents for temperature regulation, with heat from metabolic activity driving a chimney effect that circulated fresh air from the surface. Refuse chambers were positioned at the periphery or base to minimize contamination risks to the queen and brood chambers located deepest.

The cement casting technique, involving 3,500 to 10,000 kilograms of mix, has proven more effective than traditional excavation in preserving the intricate three-dimensional layout of ant nests. This method allows scientists to study previously inaccessible structural and behavioral aspects of social insect architecture.

Researchers plan to continue analyzing the cast to better understand soil mechanics and tunnel stability in biological systems, with potential applications in civil engineering and robotics. The study highlights the advanced collective engineering capabilities of insect societies.