Green Bottle Fly, a common fly of the genus Lucilia:

I usually learn something new with each of these super-macro sessions. The lesson in this case was that specimens do not last forever in the freezer! I have collected a green bottle fly some months ago and finally got around to preparing it for photographing a few days ago. When I got it in the camera's sights I found a dent in one of the eyes plus the cells in the compound eyes looked very irregular. Looking very closely I realized that some fo the cells int he eye had collapsed - they no longer bulged slightly outward, but rather some cells now sank back into the eye. Some cells had gone from convex to concave, and so reflected light differently and created an irregular aspect to the celll pattern of the eye. Snatching a fresh bottle fly off a leaf and photographing it a few hours after collection revealed a very regular pattern to the eyes. 

So - at lease some insects must be fresh to get good results when photographed, or perhaps I need to find an alternative method of storing them. 

This photo was made from 154 stacked images at approximately 5x lifesized.