Hey Jose, I wanted to show you what this image looks like with the darker tones intensified. All I did was do a levels auto adjustment in CS4 and then added a multiply layer over the top. See the difference?
In your image I feel the front of the butterfly gets lost in the whites of the flowers. Here I think more of the butterfly is illuminated and really stands out against the beautiful blue background and the whites of the petals.
My guess is you probably didn't need the flash for this image - it certainly looks light enough outside to make the image without it.
This is a Red Admiral butterfly. I expect the flash was needed to capture this image at f/18 and 1/250s shutter speed. Any less dof and the flower blossoms in the foreground would be more oof and a would be a real distraction. in fact, a crop removing the bottom to a more square presentation would eliminate the most oof blossoms. Some darkening of the image would improve this image but less than that presented would be my suggestion for improvement.
Good sharpness and I like your comp, Jose. Julie's repost is a little too dark for my taste (though it could be a monitor thing), but something in between the two versions might be very nice.