Lepidopteran Lexicography

I happen to know the word for "butterfly" in quite a few languages. This is not because of any particularly profound interest in these winged creatures, but rather that they, like hearts and flowers, have a tendency to turn up a lot in popular songs - as symbols of female beauty or of male fickleness, as the case may be.
However, there is another striking thing about these words.

English : Butterfly

Swedish : Fjäril

Danish : Sommerfugl

German : Schmetterling

French : Papillon

Italian : Farfalla

Spanish : Mariposa

Portuguese : Borboleta

They are all totally different! Even in closely related Western European languages, where otherwise most terms tend to derive from a common Romanic or Germanic root.
I have no idea why this is, and don't know any other examples like this.
Apparently, the Dutch word is "vlinder", which once again is completely unrelated to the rest, but this is the only one I had to look up in a dictionary so I cannot really vouch for it. I guess I don't listen to a lot of Dutch popular music.