I got really confused because there were so many butterflies flying around, so this was difficult to spot... I don't know if this is a bug or just an oversight. Some butterflies, after I massaged them, the massage option was still there, so I couldn't tell if they were ready for milking. After I got around to remembering the name or could keep my eye on the last one I massaged, I had an easier time of this. The massage should always grey out when it has been done and you can milk the butterfly. There were several butterflies that I milked while the massage option was still highlighted and available.