So delicate and lovely in every way! Great details on the butterfly, great side view, nice simple perch (love the fine hairs on this!), nice natural light and soft muted bkgd.
Nancy said it! Beautiful! My take would have been for a little more at the top, and maybe a little less at the bottom, although I like the way the stem becomes less attention-grabbing near the bottom edge -- darker and less detailed.
Excellent shot, though I'd echo Allen's suggested expanded crop up top. I'd have liked a little more DOF on the near wing, too, but as a 7D owner I understand the tradeoffs. From the noise and the whites my guess is that you could have exposed a little farther to the right to improve things a bit. But all of that's being picky. Good work on a beautiful subject.