Basically, this is just "giant ants could be added because awesome". If you're gonna present a mob idea, then actually explain it better. Telling us the mob's name and then just declaring your own idea as "awesome" is not how you do it.
Sorry I was pretty tired and my brain was joining dots with what they have done with current mobs and new environments. In real world the large caves are a natural environment for ants. the new mobs are natural predators to ants when they are young (seen few wild life docs on it) and when they become adults they focus on fish and other larger food sources. The direction of environment and current mobs could see new hostile or passive hostile mobs in the form of ants implemented to the game esp if based on the spider mechanical movements combine this with a precession of mobs at certain times of day it could become crazy mob hoards esp if an ant is accidentally killed and the troops retaliate in mass numbers like army ants
Points for making the effort to add to your idea, though you should put that in your first post. I can't say I'd mind if the idea was added, but I - and this is just out of pure opinion - find having large ants in the game as not the most original idea in the world. I'd suggest adding more to the detail of the idea such as damage values, the names of any ant variant, etc. so everyone has the exact same vision to your idea as you.