Hey, that's a great question you've got up there! Calm down, butterflies don't sting. You could spend an entire day surrounded by them and not be afraid in the slightest. The fact is that for themselves, the primary source of nutrients often become sap and other plant juices: they generally drink nectar or like miners go looking inside flowers for sugary secretions.
Their can't-go-without meal, true, is liquid: nectar from flowers and fruit juice are loaded onto the proboscis and sucked. When a thirsty butterfly sips nectar from a flower, it sticks out its long straw-like snout, called a proboscis. This 'sipping' is done with their mouths close to the object of desire; that is why butterflies have no teeth. So there 's no need to be frightened of a butterfly's bite the next time you see one.