The origin of English names:
Why is a butterfly called a butterfly? The reason is that the etymology of butterfly comes from the old English butler, which consists of butter and fleoge.
There is a long-standing saying that butterflies like to steal cream and milk, so people say that they are elves with colorful wings and like to steal cream, so they are called butterflies. The above legend is also reflected in milchdieb, one of the German names of butterflies, which is equivalent to milk-thief in English.
Another explanation is that the butterfly refers to the color of the butterfly; Fly originally refers to flying insects, and the word butterfly may first refer to a sulfur yellow (the wings are closer to cream color when closed) pink butterfly in southern Europe after winter. The male butterfly's front wings are orange, which brings warm light when flying. It is called butter-colored fly. The word butterfly has gradually evolved to refer to all kinds of butterflies.