Thank you very much for your critique and your honest opinion. I really appreciate it and find it very useful.
I agree with you that a smaller aperture would have allowed a deeper DOF. However, from the informations I posted in the notes section you can easily find that a smaller aperture would have resulted in too long a shutter speed to shoot handheld. Since I left the tripod in the car it was a "take the picture or leave it" situation. The butterfly would have only spent a second or so before leaving the flower anyway which would have made the tripod useless. This was the compromise I had to make. It isn't always possible to create the best shooting conditions in the field. I'm happy I could take this picture even if it's not perfect. I hope you liked it too! Thanks again!