The Forgotten Planet by Murray Leinster

The army ants flowed over the ground like a surging, monstrous, inky tide. Their vanguard reached the river and recoiled. Burl was perhaps five miles away when they changed their course. The change was made without confusion, the leaders somehow communicating the altered line of march to those behind them.

Back on Earth, scientists had gravely debated the question of how ants conveyed ideas to each other. Honeybees, it was said, performed elaborate ritual dances to exchange information. Ants, it had been observed, had something less eccentric. A single ant, finding a bit of booty too big for it to manage alone, would return to its city to secure the help of others. From that fact men had deduced that a language of gestures made with crossed antennae must exist.