I like that one a lot. Great colors and wonderful sharpness. Good exposure.
I think you made a very good compromise between a calm BG and enough sharpness on the butterfly. This is often one of the hardest problems with
butterflies.
Agree with Mike on the BG - softer and lighter might put even more emphasis on the butterfly and thistle plant - but it's very well done overall. Even though the top edge of the front wing is a bit blurry you did a great job of getting the head/eye/antenna sharp and that makes a world of difference. Way to go!