Here are links to the videos in which you will need to know, to perform this stitch.
Bullion Knot Stitch, to make the abdomen of the butterfly:
Lazy Daisy Stitch, to make the wings of the butterfly:
by Vaani Mehrotra
by Shagufta Fyms
by Vijaya's Art
by vasuki rajEmbroidery
by Proficiency Knowledge