The rumbling coming from the deeper tunnels meant only one thing. The guardian ants had gotten wind of what Walker and Midnight had done before retreating. They had found the destruction and began to rampage at the orders of their queen. The guardian ants were raised specifically to protect the colony and the queen. The soldiers were nothing in comparison to them. Forget any ability to gather food or to dig. These guardian ants had none of that.
Instead of these characteristics, the queen had raised them with battle and defense completely in mind. That meant much tougher carapaces and higher strength. Where the bear golems were meant to be shields and hammers, so were the guardian ants.
drop those golden tickets!