Surprisingly, butterflies do not eat any food, they only drink nectar! Butterflies do not have mouths, they have a long straw like structure called a proboscis which they use to drink nectar and juices. When not in use, the proboscis is coiled up like a garden hose.
Since they do not eat, they do not excrete any waste, which disproves one theory that they got their name “butterfly” because their poop looks like butter. Simply not true! If butterflies take in too much liquid it is expelled through their abdomen.