Fun game!
I couldn't really figure out what the score was coming from. I thought it was the bug kills, but it appears to just go up over time. I killed a few of the (creepy) caterpillars, so I feel accomplished. Final score was 80, with a couple thousand mycelium.
Only real issue I had was that the caterpillars don't get slurped into the group by the fungus, but otherwise it worked great!
It would have been nice to see the health of the walls / turrets for that tension of "I'm going to have to replace that wall in a moment", and perhaps a speed up mode would be cool.
Nice job!