There is an awful lot of redundancies / repetitive expressions. I do understand that this is for children and should be clear, but an editor would trim this substantially without anything being lost.
Another issue: This work is already available on the Internet, at least snippets of it, as the book is previously published. You will likely run into problems with duplicate content filtering and penalties as described in the HubPages FAQ.
I find it very difficult to have empathy for a fly. Having said that, I think that the story is fine but wordy. It might be written for too old a child. I think the story is akin to The Little Engine That Could.
The children that would like this, are probably more picture book age. That means a lot less words and lots of illustrations. Also, does it make sense to get the child to relate to the fly and his challenges and disabilities and then end up being killed? I don't think so. As an adult fairy tale, it might fly, (pun intended) but for a child, I don't think they could appreciate the irony. They may draw the conclusion that if they are different, they are going to have a very hard life and then get squashed and never be able to succeed.
The story needs to end with the little fly's success. Children that would like the story are likely to think in very concrete terms.