Hi Mark,
 
If you can't get near them to requeen then killing them is an option.
Our black bees can be quite vicious, and I have been tempted on several
occasions, but only killed one lot which were bad tempered, and very
queenless.
 
On killing bees, I have found that 500ml (1pint) of ethanol (Vodka) in
the top of the hive, then plug it up, kills them all very quickly. You
can then air the frames, and they are as good as new. This does not
happen with petrol (gasoline) where no matter how long you air anything
it stinks for years.
 
Do not use anytihng with Methanol in it, Vodka is food grade and more
expensive but safer.
 
 
I hope this is of some help.
 
Steve Pearce
Kilspindie
Perthshire
Scotland