How did the ant know that the army it saw was the army of Solomon (peace be upon him)?

A Muslim must safeguard his heart and religion by avoiding argumentation with non-Muslims that might instill doubt in his faith. He should glorify Allah and His Messenger, and believe all that Allah has revealed. Allah has indeed narrated in Surat An-Naml the story of the ant and its intelligence and sagacity in its saying: "O ants, enter your dwellings that you may not be crushed by Solomon and his soldiers while they perceive not." This concise advice encompassed ten types of discourse, which astonished Solomon (peace be upon him) and made him smile and thank Allah.

Allah has inspired creatures; the ant knew Solomon, just as the hoopoe knew him. And Allah revealed to the bees: "And your Lord inspired to the bee, 'Take for yourself among the mountains, houses, and among the trees and what they construct. Then eat from all the fruits and follow the ways of your Lord made easy.' There emerges from their bellies a drink, varying in colors, in which there is healing for people. Indeed in that is a sign for a people who give thought." This revelation is the inspiration of creatures for what is in their best interest. Solomon (peace be upon him) was known among the creatures due to the greatness of his kingdom, just as our Prophet Muhammad (peace and blessings be upon him) was known to rocks and trees.