The demigods began to realize a lot of things. First, they are not strong. It only looked that way because the royal guards were acting weak. Second, they didn't push the royal guards back. It only looked that way because the royal guards wanted them in the ant mound. And three, nothing was holding up the reinforcements for the royal guards. It only looked that way because the ants were waiting to ambush and trap them.
But these realizations only brought more questions about why the royal guards are so strong and how they were able to hide from them. It is all too late now to get answers to those questions anyway. The six royal guards pressed them from all sides and culled their numbers one by one. Their approach was careful and methodical almost like pruning shrubs. They cut down everything in front of them and made sure it is dead before moving on.