Termite soldiers have even bigger heads than army ant soldiers, in part because, unlike ants, they do not need to run long distances. Instead, they position themselves at the entrances to tunnels, biting anything that attempts to enter. … By restricting access to a small number of tunnels, termites remove the numerical advantage of the army ants, forcing their soldiers to confront termite soldiers in duels the termites are likely to win.

Emlen, Douglas J, Animal Weapons_ The Evoluti…, loc. 970