The result of my attempts to get the shader of my recently found fly object's wings right.
I used three versions of three populations of flies (Two pops from above with different seeds and one frontal one). First the flies with the wings' shaders opacity set to zero, the second pop with every shaders' opacity set to zero except the wings, but with "cast shadows" unchecked, and the third pop, which is almost the same like the second one, but with "cast shadows" on, and "invisible" plus opacity set to 0.6 to get less opaque shadows of the wings.
The poor guy, which I have used a lot of times, is from Ten24, and although his facial expression is quite special, I always find scenes where I think he fits in.