Have to say, IMHO, I like the composition; my eye is immediately drawn to the purple flower, then up along the proboscis to the moth itself.
In contrast to the comment about the subject being too near the top, I'd perhaps have cropped it a bit more so the flower head is at the centre of the top left cross of an imaginary Rule of Thirds grid, if that makes any sense? Though I do tend to be a bit on the crop-happy side!!
I'm intrigued by the logistics of the shot, 'cos my macro attempts are always hampered by the blasted subject buzzing off about 1/2s before I hit the shutter. How long did you have to wait to get the shot?