I love this! Very cute and soothing, and the art is just lovely. It's so much fun to see the subtle variations that can happen with color and pattern and wing shape.
One question, though: I noticed the shape of the lower wings seems to get locked in within the first couple of generations. Once I've chosen a triple-tailed butterfly, for instance, it seems to be impossible to reintroduce single-tailed wings, no matter how many generations I spend breeding with single-tailed parents - and vice versa! Is that the intended behavior?