The easiest way to work out how fast a bee beats her wings is to find
somebody musical who can tell you the note that is produced.  For instance I
am told (not being musical myself) that the honey bee in normal mode produces
a note close to middle C which (from memory) is 256 beats per second.  I was
talking to a would be beekeeper once who, having a good ear was able to
distinguish between the sound of a normal inquisitive bee and one that was
about to attack.  She did say what the note was but I have forgotten.  You
can also buy electronic tuners which would probably tell you but I don't know
if they are as good as an expert ear.

Chris Slade