Hi Fiona,
This is quite a striking image, although I think it is fair to say that it is the fly itself that is bringing all the sparkle to this image. Those big green eyes and whiskers offset against the amber coloured body and legs make this fly and intriguing subject.
Now, technically I think this image is close to perfection… the subject is sharp and the exposure is near enough to perfect. At this stage there are only two things that I would be inclined to do to the image.
The first is to slightly lighten the underside of the fly’s tail section; it is just a bit dark and it would add to the balance of the image. To do this, simply select the tail with the Lasso Tool (make sure that the Feather option is set to about 20 pixels), and then go to the Curves panel and gently pull out the middle of the Curves panel so that lower section lightens up.
The second item I would adjust is the cropping. The image is just a bit cramped in the lower left corner. If you have an uncropped version of this, I would revert back to that. The other option is to expand the canvas in Photoshop and then gently clone the background back in.
Now, as perfect as this image is, I think what you have to ask yourself now is, what happens the next time I encounter a fly like this? How can I improve on this image? I think next time you need to be thinking about a second element within the image, something that helps tell the story. This challenge will set the bar even higher for you… but if you can make images like this, I think you can rise to the challenge!
Cheers, Anthony