Hmmm... interesting.  Well, the scent theory is *supposed* to work, but I
know there are exceptions.  I remember watching in amazement as one of my
cats watched in wonderment as an over fed mouse tried to make it out of
the cat food bag under the kitchen sink to the hole by the drain pipe.
I'm telling the cat, who had apparently never seen a mouse, to "Get it!",
meanwhile, the very plump mouse keeps falling back down and can't make it
to the hole he came in through!
 
But, when it comes to blocking holes, use steel wool - rats and mice
can't chew through that.  You can even use steel wool in conjunction with
expanding foam.
 
Gary
[Posted in FML issue 4342]