I have never seen one but have often considered the idea.  I work in
electronics and believe that the solution is to glue an RF ID tag onto the
queen's thorax.  The antenna is limited in size by the thorax size.  An RF
ID tag is the kind of thing they are using to track pallets, luggage and
packages in new facilities.  Every item in  a warehouse can be inventoried
and located by this technology.  The advantage over bar-codes is that the
package does not have to be in a particular orientation to read and it can
be read from a large distance.  They are developing low cost ones that can
be put on grocery items so a filled cart can be wheeled past the
interrogation antenna and a complete list of everything in the shopping cart
can be generated and billed. The concept would be for a handheld
interrogator like a radar gun would be aimed at the hive to interrogate the
RF ID Tag.  A response would show that the tag was still in the hive.  Since
dead queens are dumped outside, a superceded queen would have the tag
missing and no response.  The response could contain an individual ID number
or even data on the queen breeder and the year of birth.  As the hive is
opened, the scanning could be over a single frame to pin-point the queen.  I
worked the design a while back and found it un-economical.  Too often the
realization of something is limited by economics rather that possibility.

 Raymond J. Lackey                           Sweet Pines Apiary
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