"fly", Ger "Fliege" (the insect drosophila) could theoretically reflect an earlier *plag. It is linked with "to fly" though, to nobody's surprise.
Old English flȳġe, flēoge (“a fly”), from Proto-Germanic *fleugǭ (“a fly”), from Proto-Indo-European *plewk- (“to fly”)
But maybe there is more to it. How does it compare to flea and eitherway to plague?
plague is a biblical symbolism, isn't it?