Nice job, and a challenging specimen to start with!
Those long bright hairs at the bottom of the face are an invitation to trouble for most stacking algorithms. Bright hairs/bristles competing with a dark surface either in front or behind them are very prone to halo and visibility errors. If I had to guess, I'd say I'm seeing both in this image. Unless this fly has bristles on the lower parts of its eyes, and nowhere else, then those bright bristles that appear to be coming
from the eyes are actually
behind them, being seen around the eyes when the lens is focused farther back. If that's a correct interpretation, then about all I can suggest is manual editing. At present, I'm not aware of any programs that will correctly and automatically handle that situation.
The OOF bristles in center at top of head are confusing. I can't tell whether they go backward or forward, and whether they are in front of or behind the other large bristles arching in from the eyes. I suspect visibility errors in the rendering, but I can't tell for sure looking only at the final composite.
The whole thing seems to be a little fuzzier than I'd expect from the lens that you're using. Often a bit of sharpness gets lost in resizing to web resolution, and I wonder if this happened to you? If so, the appearance can be recovered with a modest sharpening after resizing. In Photoshop, I usually apply around 35% at 0.7 pixels just before the final save.
I agree about needing some more lighting from below -- at least enough to show the ommatidia even on the bottom of the eyes. But the lighting you have is working great for the upper part of the face. The colors, surface texture, and iridescence look wonderful!
It's a very nice touch to use a leaf from the natural surroundings for background.
How did you transilluminate the leaf, and illuminate the subject, while maintaining color balance?
--Rik