>>No such substance exists.

One person suggested almond extract.  If it does deter bees (I have never used it), it may work just fine with periodic re-application by the homeowner.  

>>You should come to one of the 
Long Island Beekeepers meetings
http://www.longislandbeekeepers.org
and ask the more experienced bee removers like the 
Bloom brothers.

I wish I had more time to go to meetings but one does not need to go to a meeting to speak to someone... :-)  I know and periodically speak with Rich Blohm.  I do AT LEAST the same number of removals.  Not to be arrogant, I get called to remove colonies where others said they would only spray.  Some darn property owners just don't want to kill honey bees...

Waldemar

****************************************************
* General Information About BEE-L is available at: *
* http://www.honeybeeworld.com/bee-l/default.htm   *
****************************************************