It's nice, if a little plain. More interesting colors (like the others said) would be good. Another issue is the shadow. Check out this edit. Not really an edit, I've just added a few lines connecting the shadow to its corresponding place on the fly. If the light source is the sun, these lines would be parallel. If not, then they should converge to a single point (approximately), that point being the light source. As you can see, your shadow is a bit off (even though it doesn't really appear to be at first). Just something to think about. The overall piece is pretty good, though.
Nice illusion of transparency you've done there with the wings. You need to use a reference from a real fly, and make more flowing designs. Use colors which are interesting, as well as more contrast as zi-double's mentioned. To achieve really high contrast, i generally find it easy to start with a black background, then block in the base colors. Then, immediately put some pure white highlights on the shiniest parts. You then will be aware of the full contrast you can do, and you'll make your whole piece in that manner.
see what I say in previous work - contrast needed ... in eyes - light, in body - dark ... hm I suggest to try with small scale will be easy to repair mistakes to test and to try some diferent ... also that different colours which use with click me make your preview to look poor ...
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