Answer:
Weight in my belly trees on my back nails in my ribs feet I do lack.
I can make arrows fly. I can make kites soar. What am I?
The more you work, the more I'll eat.You keep me full, I'll keep you neat. What am I?
I have no wallet but I pay my way. I travel the world but in a corner I stay. What am I?
I'm sometimes white but most often I'm black. I take you there but never bring you back.
No matter how little or how much you use me, you change me every month.