Answer:
I grow where no flower grows, where no light touches the walls, up or down, that I don't care, was here before people were.
I fly through the air on small feathered wings, seeking out life and destroying all things.
When the creeper passes, all the grass kneels
My second is performed by my first, and it is thought a thief by the marks of my whole might be caught.
Until I am measured I am not known, Yet how you miss me when I have flown.
What never gets any wetter no matter how hard it rains?
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?