Death throes of flies: Why so loud? [new title]

Something that drives me nuts is to hear a fly die. Why do they flop over on their back, buzz and spin in circles before bitting the big one? It seems like a very painful way to pass on. Any idea?

WAG: They end up on their backs because they are sick and disoriented, they buzz and spin in circles in a vain attempt to get back on their feet.

Welcome to the SDMB, coldstreak753. We appreciate descriptive thread titles so I have edited yours accordingly.

moderator GQ

If you only had about a month to live, wouldn’t you put up a kick at the end?