I introduce many(!) virgin queens using plain bee-o-logy. With almost 100 % success. No smoke, nothing fancy. Just dequeen the hive, wait 2-3 hours and introduce the queen from top of the frames. That's it.
Bees need some time to realize that the queen is gone. Usually in a strong hive with brood present, that'll take 2 or 3 hours. The bees then panic. In this phase they accept anything, be it virgin or mated queen. Old queen, queen cells. Whatever, as long it is something queen.
Once the panic is over, at latest at midnight, the bees start an emergency queen raising plan. Once this sequence is started, it is much more difficult to introduce a queen. Because the bees want "their queen". From then on the beekeeper works against the bees. Please note: completely unnecessary...
And devices like cages, introduction cages, waiting 1 day, 9 days or even 2x 9 days, smoke, whisky dipping of the queen, or a lot of other hair raising "techniques" are invented to compensate for complete lack of bee biology knowledge.
Also note, that I use the dequeen+2hours-method all around the season. Be it Spring, Summer or autumn. Or rainy, hot or whatever. :thumbsup:
Also note: in all sorts of hives. Splits as well as full hives. Works with all bees.
PS: I prefer requeening in the evening. Dequeen at 7 pm, requeen at 9 pm. Or so.
PPS: I keep virgin queens up to 10 days in the incubator. You better feed gelée royal and honey mixture 1:1. You get better queens. I'll upload a video on how I feed the queens in some weeks.