Utilising spare honey bee queens caused by over production or more successful production than had been anticipated
Raising queens by grafting is such an easy process that you will often be faced with having more queen cells available than you have mating nucs to put them in. Do not waste them, if you cannot find a method to utilise them within your system, give them to a neighbour, at least that way you will have the benefit of some of the genes that you have selected, coming back your way in future generations as Drones.
One way that we could save a few for ourselves is queen banking, but before we can make use of this we have to get the queens mated. There is a technique that can help in this situation in order to speed up large scale queen rearing it is common to place caged queencells in a mating nuc a few days after the first cell was added. This is so the virgin can emerge and be ready for release after the first queen gets mated and is removed for sale or use elsewhere. It is possible to put one cell in a cage and the other merely protected, again as soon as the first one is mated, she is transferred to a banking cage and the caged virgin is released for subsequent mating, as this does not allow any time for the mating nuc to be laid up, the nuc will dwindle a little in bee numbers, but you will have surplus mated queen instead of just spare cells or virgins. The time penalty may not be very great as both the loose virgin and the caged one will mature at the same rate. So as soon as the first one is mated and removed it may only be one or two more days before the second one achieves mating. As both queens are in the nuc together there is no need for any special precautions in releasing the caged virgin after the first one is removed.
Disposition of cells within a nuc I have some mating nuc frames that are equipped with Nicot cell plug nipples, they were made for banking small numbers of queens in mating nucs, but they lend themselves perfectly to this process and although I have not tried it, I reckon two caged virgins could be used allowing three queens to be mated in quick succession.
Using a queen banking frame for sequential emergence/release of queens
If you still have too many cells and nothing you can do with them, they can be turned into a queen pheromone lure. Allow the queens to emerge into cages, freeze them and drop them into alcohol (surgical spirit or rubbing alcohol) in a screw topped glass jar, add any dead queens that you may cull at a later date, allow the mixture to stew for several months, the resulting liquid will be attractive to bees and can be used as a swarm lure.