Great job with the butterfly; IMO you could add some shadows to the background and use a colour more of black or gray than brown. Otherwise its amazing Good luck!

Thanks for the feedback Lamantine, good luck with the book.
I added a subtle shadow but kept the background plain as it would be easier to add whatever text for the book cover that way.

Thanks I wish you good luck for the contest, its better now

Desaturated the image at 60% to reduce the brown look

I like the change as well, seems more moody and ominous now.