Similar to what Garth describes using car exhaust to kill bees would be to
get a tank of CO2 and after closing all entrances and cracks, give them the
CO2 from the tank.  In the beginning it will knock them out (like an anesthesia
) and then if you continue doing it, they will suffocate.  I would imagine bees
would probably die pretty fast if they can't breathe.  Almost all insects have
an automatic response to Carbon Dioxide, which is to breathe more.  They can't
stop breathing.  That is why we always used CO2 to knock out and anesthetize
insects before using them in experiements in our insect physiology class.
People who collect hornets nests use it to knock out the hornets temporarily
while cutting down the nest and putting it in a plastic bag for transport.
People who want to safely store grain in an airtight container often will put
dry ice in the bottom.  As it sublimates and releases CO2, this dispaces the
oxygen because the CO2 is heavier than oxygen.  Any insects in the grain will
be asphyxiated and die.  Then you push the lid down tight and will not have
any insect problems in the grain.  I imagine you could put a piece of dry ice
in the bottom of the hive and seal up everything airtight (as much as possible)
and also have the same outcome as Garth describes (it ought to take an hour or
more for the dry ice to all sublimate).  I would think that the dry ice would
cause no lingering problems of toxicity or smell, etc. such as might be caused
by using petrol (gasoline for Americans) or burning sulfur fumes or one of
many other alternatives.  I suppose one could even use chloroform if one had
any.  Dry ice seems to me to be the cheap and easy way to go with no toxic
after affects.  I probably wouldn't have thought of it except for Garth's post
on using car exhaust.

Layne Westover
College Station, Texas