The proboscis isn't a straw, it's a paper towel
The long, curled, tongue-like body part of a butterfly is called a proboscis. A butterfly can unfurl the proboscis to get at the nectar of flowers and liquids from fruits and other foods. But if you thought it was weird that a butterfly feeds through a giant curled straw, well that isn’t even the weirdest part. Despite what you might have seen in cartoons, the proboscis doesn’t actually act like a straw at all. A study by Konstantin Kornev of Clemson University illustrated that liquid is too thick for butterflies to be able to suck up in such a way. Far more pressure than a butterfly could produce would be needed to do so. What actually happens is that liquid is drawn up through capillary action — something more accurately compared to when you dip the corner of a paper towel into a bit of spilled water, and the water runs up into the towel, soaking it. Tiny grooves inside the proboscis pull the liquid up the tube and that is how a butterfly actually drinks. Amazing. And weird.