These realistic butterflies are from the DIY Blog Radiantik . The paper butterflies are colorful and large. If you print these, you should use stronger paper, so you can cut out the fine details. I can recommend paper with 120-140 g/m². This way the butterflies have a better structure and can be folded without creasing. Also with stronger paper the paper butterflies containt their shape/fold.
Some handdrawn vintage butterflies from an old german book about european butterflies.