Soldier ants were made for the sole purpose of protecting Queen Regina, hardly ever leaving the hive’s cavern network. They are incapable of direct speech, having no need for it. While still part of the hive mind, soldiers don’t add much input to it, their default state being that of ‘protect hive’ and ‘kill things that are not ants’. They are essentially a living security system. Their blood is acidic and poisonous, mostly useless as a product since it’s hard to contain outside of their bodies.
After Queen Regina’s death, soldier ants could no longer serve their singular purpose and were remade into war abominations. Their shapes can range from humanoid to massive, living siege engines. They now guard outer settlements, borders, the new Queen Beata Regina, and venture out in droves to recover organic matter for the production of more ants. A single ant is often accompanied by at least one soldier at any time. A disconnected soldier ant can no longer reconnect to the hive mind; it exists only to kill and die.