Because that is what it does...

Schmetterling, farfalla, papallona, borboleta, mariposa, papillon, tximeleta, petaloúda, sommerfugl, tauriņš, fluture, perhonen, féileacán, pillangó, vlinder, urukurubụba, paru paro, npauj npaim, papilio.

All these words say butterfly in different languages, but I think they really mean:

Flutterby...