Nice one!
I'd suggest something like a mechanic where you have limited use of poison clouds to make the game a bit harder.
But cool idea overall.

Not bad! I found how the world abruptly ended breaks the illusion of the game. However, its a pretty good game loop. You could try turning this into an infinite game, you got to stop all the ants but new colonies keep emerging. Adding a timer to when you can attack next would be a nice quality of life feature but not needed. Well done!