Hello Judy, David & all,
 
I've been using a MUCH easier method to destroy robbing yellow-jacket
hordes.  Read my post on this subject in the alt.sci.beekeeping
news group or below:
 
Take a bottle & fill it 3/4 the way full of water (I use Arizona Ice-Tea
 
bottles....as the neck works perfectly to keep them inside the bottle)
and then add approx. 10-20% of raspberry or blackberry jam (about 6
tablespoons to an Arizona Ice-Tea bottle).  Place the bottle anywhere
around the hive.  Yellow jackets seem to prefer to climb into
hard-to-reach places so I've had the best luck in placing bottles about
3-4" under the landing boards (or behind the hive if you wish to attract
 
the pests AWAY from the hive opening).
 
Leave the bottle for a few days & return to find 100-200+ yellow jackets
 
drowned inside the bottle.  BE SURE to check the bottle every few days
as they'll be able to eat the jam-solution if there's so many dead
bodies there that they can remain afloat on top & fly away with your
'yummy' jam treat.  Bees will ignore the jam.  You could even place the
bottle inside the hive if you wish, though curious bees might find their
 
way to the same demise.
 
Good luck,
Matthew in Castle Rock, CO
 
 
 
David Gaida wrote:
 
> Dave says he is going to invent a yellow jacket smasher.  It will
> consist
> of a small weighing scale on the landing board that detects the yellow
 
>
> jacket as underweight to a honey bee.  A very small hammer will then
> come
> down and smash it.  Still on the drawing board. :-)  It has got to
> beat his
> standing up by the hives every evening since we realized our robbing
> mistake for an hour with a fly swatter.
>
> Judy in Kentucky, USA