Answer:
When they are caught, they are thrown away. When they escape, you itch all day.
I know a word of letters three. Add two, and fewer there will be!
By Moon or by Sun, I shall be found. Yet I am undone, if there's no light around.
It is weightless, you can see it. If you put it in a barrel it will make it lighter?
Give it food and it will live, give it water and it will die.
It rows quickly with four oars but never comes out from under his own roof. What is it?
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?