Ants: can have a colony in grass and dirt blocks ranging from 1x1 blocks to 5x5 blocks. queen ants usually hide out unless it is time for their nuptial flight (as you said, around every 5-10 days) ...
I'm going to expand on this idea in another post. it's a really good idea but i think i have behavior, health and some more things that may be ok! good suggestion!