Butterflies live on an all-liquid diet.
Their mouthparts are modified to enable them to drink, but they can't chew solids. A proboscis, which functions as a drinking straw, stays curled up under the butterfly's chin until it finds a source of nectar or other liquid nutrition. A butterfly cannot live on sugar alone—it needs minerals too—so it will occasionally sip from other sources which are rich in minerals and salts. This behaviour is called puddling. That’s why you can see butterflies drinking from mud puddles, or even on animal poo sometimes.