Garth wrote
 
> One was an Australian patented pest repellor, that plugs directly
> into the wall socket. It then uses electricity from the socket to
> send a low frequency electromagnetic pulse through the house wiring
> which apparently then drives all cockroaches, rats etc away. The
> pulse apparently tinkers with the workings of these animals sense of  
> direction amongh other things.
>
> Has anybody tried one of these for chasing bees away?
 
There was one advertised in Australia that said it had been tested by the University of Queensland and found to be effective against cockroaches.  Not sure if this is the one you saw, Garth.  My wife rang the University to contact the person who had done the testing and after being transferred from Department to Department, could not find anyone who knew anything about the testing.
 
We didn't take it any further and I have not seen the advertisement since.
 
Trevor Weatherhead
AUSTRALIA