This is a chart of the mitred square pattern for my Mitred Square Butterfly Blanket (full instructions for blanket are at http://funthingstodowhileyourewaiting.com/2014/01/29/mitredsquareblankie/). The purl symbols on the 15th and 21st rows represent the Butterfly Stitch: Pass needle underneath horizontal floats from the bottom to the top, knit next stitch bringing new stitch back out in front of these floats so they are caught in the stitch.
Shown with a cast-on count of 49 stitches.