I make the distinction between a 'dry queen cell cup' (meaning it has no egg or larvae in the cup itself) vs a 'queen cell' (which does have egg, larvae or is capped and will fairly quickly produce a virgin queen). This is somewhat important since a lot of new beekeepers see the 'dry queen cell cup' and automatically assume their hive is going to swarm. I am not certain anyone really know why hives produce dry cups and some seem to produce a few and some many.