As you go through your hives and change out old queens for new ones, drop the old queen in a small jar (think baby food jar) that is about 1/2 full of alcohol. the pheromones will leach out into the alcohol, use a Q-tip to dip into the solution and put in your bait hives.
A combination of LGO, an old brood comb and a lived in box or nuc is what I use. I caught 17 swarms last season with two traps so now for this season I already have 20 traps out. Let the bees swarm! :yahoo: