Subject: How long does it take a cocoon to hatch out?

I found a cocoon in my hard that had fallen from a tree after a recent 
hurricane , I wrapped the stem around a nail and hung it from a post.  
Whatever is inside is still alive and moving, but it's been about two 
months.  I'd like to see it hatch, and my 4 year old son is very 
interested in the whole process.  The cocoon is a solid light beige.  What 
steps do I need to take in ensuring that the cocoon does hatch out?

Re: How long does it take a cocoon to hatch out?