Blue arsed fly?

[piptik]

Is the origin of running around like a blue arsed fly just from buzzing bluebottles or is there a more interesting origin?

[Quizmonster]

There was an old song of the American Deep South all about the "blue-tailed fly". From the song, it's clear that such insects were a blasted nuisance, having to be continually brushed away by servants...even, in the end, resulting in the Master's death after falling from his fly-pestered horse.

I'm sure the version, such as you offer in your title, is just the somewhat cruder British version of the same idea...something constantly buzzing around.

[rara_rogers]

I was told by my gran that if you watch a firefly, it flits around like crazy, like the ones in Sherwood forest. Fireflies apparently have a blue glow (unlike glow worms that have a green one!) hence the phrase!

[Quizmonster]

I think it's far more likely that the creature in question is a bluebottle, as Piptik suggests. This is a fly of the Calliphora genus with an iridescent blue body...ie one that looks blue all the time rather than just in the dark like a firefly. To see them buzzing endlessly around - just like the busy, busy person we compare them to - simply put some rotting meat out...and watch!