Fly's lay eggs on carcasses and hatch into maggots that help to clean up the mess. I'm sure there may be critters that are willing to feast on maggots. Maggots become flies and repeat the cycle while in this stage feeding other life.
Frogs lay eggs which may feed animals such as snakes. Eggs hatch and become tadpoles which feed other life as well such as some birds. They then become frogs which become food for cats, herons, ECT.
Animals such as Gypsy moth larva can strip trees of all their leaves.
I'm not sure such a thing may even be put into the game as it complexes things a bit and requires more art, but if it were to be incorporated into the game somehow I think it would work to place and adult on top of a larva stage card kind of like the Pokémon evolution, but this could effect the food chain setup of the game.