Leafcutter ants need neither a master plan nor a leader to build lengthy trails. The construction and clearing of their sophisticated highways, it turns out, relies mainly on independent efforts that add up to unintentional teamwork.

Many leafcutter ants of the genus Atta use a complex trail system — which can include many kilometres of paths — to transport pieces of leaf to their nests. The ants create these highways by removing debris from prospective trails and flattening the soil.

To better understand this feat of engineering, Thomas Bochynek at Northwestern University in Evanston, Illinois, and his colleagues used paper barricades to block ant trails in the lab and in a tropical rainforest in Costa Rica. The team observed the insects’ reactions and recreated their behaviour on a computer.

The scientists did not observe any ‘boss’ ants telling others to pick up litter. Instead, the clean-up seemed to result from many ants making an independent decision to tackle the mess.