Believe it or not, I was pixelling a butterfly just last night...scrapped it, but that's another story.
Firstly,
here's a reference. You can find way more by googling butterfly.
I'd like to point out that the body on your's is much too big compared to the wings, and that also, the bottom pair of wings go out to far horizontally.
You should also take a look at your colors. There is absolutely no reason you should be using 8 shades of a color when 2 (the brightest and darkest) can be used just as effectively with the use of dithering.
Lastly, I feel you should pick a light source. It's allready obvious that pillow shading is emerging. Just try pretending there is a really strong, focused light in one of the corners of the picture, and base your shading and highlighting on that.
I really want to see this turn out, so you better keep pixelling!