Weaver ants share a collective memory of the odours of rival ants, researchers from the University of Melbourne and elsewhere have shown. This information allows the ants to more efficiently identify and compete with rival nests.

The scientists took ants from certain colonies and challenged them with intruders from rival colonies, which were either familiar or unfamiliar to them from previous experiments. They found that when an ant encounters an unfamiliar rival, it can return to its colony and pass on information about the rival’s smell and level of aggression.

Repeated exposure to ants from the same rival nests led to increasingly aggressive encounters.