I was beginning to think that after 67 years of keeping bees that I knew enough to keep my bees happy and healthy and that they could not teach me anything new, how wrong can you be?
I was always taught on re-queening to cull the old queen, drop her back in the box, wait up to 24 hours, then add the new queen in her cage and allow the bees to eat out the candy, releasing her. Then 24 hours later check to see if she’s out, if not wait another 24 hours then release her. Then stand back and wait 2-3 weeks before checking to see the pattern she was laying, before accepting that the re-queen had been successful. This has been my standard method for years and quite literally hundreds of queens I have changed. Now suddenly I have to change my methods? So what has changed?
Earlier this year I had two hives which needed a queen change, and both could have ‘screwed up’ if I hadn’t been as observant. Let me explain and for clarity let’s call them hive one and hive two.

Hive One was a new nuc, a dark queen, active and laying, with a good pattern, just a bit too slow for my liking.
Hive Two, was an established hive which had superseded late last year, unsuccessfully as her pattern was hopeless.

For clarity, I will deal with each hive separately.

Hive One  On a Saturday morning, early, I killed the old queen in hive one, with the thumb and finger treatment and dropped her back in the box. I waited until evening and added the new queen, a quite beautiful Italian, in her cage, and the bees swarmed the cage, perhaps a little more aggressive than normal.
I waited the normal time and checked to see if she had been released, sure enough, she was out, and the hive seemed normal and quiet again.
I was a bit concerned about the swarming of the cage so I elected to examine the hive after two days, just to make sure she was alright. I was surprised to note an incomplete queen cell, complete with larvae, right in the middle of the brood area. I removed it!
Two days later I had more time available, so I decided, in spite of my original teachings to pull the hive apart, do a complete inspection just to play safe. Good job I did as I then found two other completed cells. Then I determined that the timing involved made the cells emergency queens, certainly not suitable so they were removed heeding the 4-day rule.

Hive Two followed a similar pattern. The old Italian queen was removed, cage added and examined two days later to ensure she was released. This hive had considerably fewer bees, so an early examination was relatively easy. Sure enough open cells were found at two days, were removed, at 4 days another examination showed two more.

Finally, after a few more days the hives settled down and accepted their new queens, both with acceptable patterns and hive activity.

So what was the problem, a new queen will kill off any queen cells, leaving her as the ultimate ruler of the hive?
Not true.

From past experience, we found that adding a mated/laying queen to a hive with queen cells would result in a takeover by any emerging virgins, then allowing for a non-returning queen on her mating flight would result in a lost hive. This can be a major problem when trying to eliminate a particular strain of bees, as the newly emerged queen will, in fact, be a progeny of the old queen.

There appears to be a resistance for one strain of bees to accepting a queen from a different strain, which might well have been the cause of the problems I encountered on this occasion.

Finally, I would suggest that the reader assumes a modified approach to re-queening than the standard, and re-examine any hives when re-queening to prevent the loss of new queens.