>flutterby

folk etymology, at best.

ETYMOLOGY: Middle English butterflye, from Old English butorfloge : butor, butere, butter; see butter + floge, fly; see fly2.
WORD HISTORY: Is a butterfly named for the color of its excrement or because it was thought to steal butter? It is hard to imagine that anyone ever noticed the color of butterfly excrement or believed the insect capable of such theft. The first suggestion rests on the fact that an early Dutch name for the butterfly was boterschijte. The second is based on an old belief that the butterfly was really a larcenous witch in disguise. [AHD4]