I have to agree with cure. There are a number of anatomical irregularities about his face. Which is probably why he went and did this experiment in the first place. "Screw it, I don't want to look like this. I'm going to mutate into a huge insect."
With that said, I do think you've done a decent job with the dithering and the composition of the piece itself.
try copying the half of the face you already have and flipping it. I think you'll find the eye is way off.