I would like to note just a bit of butterfly anatomy. Butterflies have four wings and six legs.
The wings and legs are attached to the thorax, the fat part of the body behind the head.
You can faintly see the division between the fore-wing and the hind-wing going at an angle up to the thorax.
Paint the dark border on the hind-wing.
Feather the colors together by running a clean damp brush along the juncture of the dark and orange.