I just came across this course and it looks really nice, even if sadly I do not speak Swedish (yet?) and so will not be using lessons 6–10.
From looking up the first butterfly in the course, it looks like the two images shown are the upside and downside of the butterfly, respectively (from left to right). Is that right? Also, is the butterfly shown always a male specimen? (To be honest I don’t even really know how much of a difference sex makes in terms of butterfly appearance.)