Why is a butterfly a butterfly?

Answer 1

O.E. buttorfleoge, perhaps based on the old notion that the insects consume butter or milk that is left uncovered. Or, less creatively, simply because the pale yellow color of many species' wings suggests the color of butter. Another theory connects it to the color of the insect's excrement.
That's not the scientific name its only a common name, each specific species of butterfly has its own name, binomial nomenclature. Binomial nomenclature is the naming of a specific organism, the first word being the genus labeling the the exact species then getting into more detail based on size, coloring, flight distance, etc. The Anglo-Saxons used the word 'butterfloege' because their most common butterfly was the yellow brimstone butterfly. This English influence was brought to the new world.