I liked building different critters for different strategies and the art is great! Fits the theme well with the Mother getting bigger as she levels. If you choose to develop it more it would be cool to see some different types of enemies/critters like maybe flying or ranged.
I did get an issue with damaging/collisions around halfway through - the enemies stopped hurting the Mother at some point (accidentally invincible) and my critters were stuck trying to attack enemies they couldn't damage (not able to return to the harvest behaviour I had given them).
Overall a fun game, nice job! :)