Answer:
Cloud is my mother, wind is my father. What am I?
You find me behind the stars; or in a sixth seventh or third. It takes something round a computer and me to make pie. I am bigger than anything you can think of.
When I am caught I am thrown away. When I escape you itch all day.
I move without wings, between silken strings. I leave as you find my substance behind. What am I?
When set loose I fly away. Never so cursed as when I go astray.
I tell people to be careful when handling boxes.