I still don't understand what has been going on here. It is a bit of a long story so bear with me. This hive contains my gentlest bees with a rather ginger queen and stripy bees. At an inspection on 01 June I found two queen cells containing larvae. I split the colony vertically with the queen and one frame of sealed brood in a brood box at the bottom, then a super, then a double queen board, and the original brood box with the other eight frames containing brood. The double queen board is a bit like a crown board with a hole cut in it. The hole is covered by mesh above and a piece of queen excluder below. There is a single side entrance above the board. The mesh stops the bees from getting through but allows the air to mingle from both sides. The board allows the possibility of developing a double queen hive.
Six days later, on 07 June, I looked in the top box and found no sealed queen cells but six unsealed cells, which I reduced to one. As a queen larva will develop in eight days from being sealed I was expecting a new queen to emerge in the top box around 16/17 June and to go on her mating flight(s) a few days later. On 09 June I looked in the bottom box and the old queen was doing well, with five frames with eggs or larvae.
On 17 June I noticed quite a few bees on the side of the hive, above the upper side entrance.
On 18 June there was a small cluster of bees on the edge of the roof.
On 19 June there was a bigger cluster.
The weather had been hot and the upper bees don't have their own mesh floor. They are also above the hot air from the lower hive so I wondered if they were overheating. It also occurred to me that they might be crowded. I expect most of the original flying bees had migrated to join the old queen below but there was some brood on seven frames above. I didn't notice or record what proportion of those frames contained brood but it might have been equivalent to three or four full frames in total. I have read that the bees emerging from a full frame of brood will cover three frames so overcrowding seemed likely. So I took off the roof and the glass quilt (crown board) was covered with bees.
The seams between frames were all full of bees as well so I added a super to give them more room. When I replaced the roof it looked like this with the cluster of bees still hanging from the edge of the roof.
When I got inside I googled "bearding bees" and found, to no surprise, that Rusty had written a post on it. She confirmed that bearding is caused by heat, lack of ventilation and crowding so I was relieved that I had done the right thing, although perhaps a bit later than I should have.
At 8 o'clock the next morning (20 June) the cluster was bigger and the hive looked like this.
An hour later there were a lot more bees on the side of the hive.
And a satellite group on the fence behind.
and within half an hour (0930) it looked like this, still with some bees on the fence.
Nothing changed until just after 2pm when the bees swarmed.
As usually happens, the bees flew over the fence into my neighbour's garden so I went round to see what they were up to. There were thousands of bees in the air and they were settling on the leaves of several shrubs but as I watched the swarm never coalesced.
After 15 minutes or so the swarm hadn't collected in one place and the bees started flying back over to my garden, so I walked the 300m to the other side of the fence. I got back to find the swarm settling on the outside of the hive it had come from.
Within half an hour the swarm had organised on the hive and the bees were settled. The satellite group was still on the fence behind.
As I watched, several scouts were investigating a bait hive about 4m away. Because of this, and because I wasn't sure where the queen would be, I decided to wait and see what happened. I was still completely puzzled that they could swarm, as I reckoned it was only just time for a mating flight of a single queen. Assuming a queen had come out I wasn't sure whether she would be on the fence or on the hive. During the afternoon there was quite a lot of two way traffic between the bottom of the swarm and the hive entrance.
Over time the swarm seemed to get smaller
and by nighttime it looked like this. I was beginning to doubt that it was a proper swarm and might be some kind of giant bearding episode.
The group of bees on the fence had got a bit larger, and I reckoned it probably had a few hundred bees.
Early next morning (21 June) there was a thunderstorm with very heavy rain. I could see that the groups of bees on the fence and on the hive hadn't changed very much overnight and were getting very wet.
By the time the rain stopped the bees were soaked.
I was out all morning but by lunchtime the bees had dried out and the collection of bees on the hive was larger.
There was lots of waggle dancing going on, both on the hive and the fence.
It was difficult to read the dances as the two groups of bees were at right angles to each other. This one, on the fence, appears to be doing a figure-of-eight dance with hardly any waggling.
Eventually my nerve failed. I swept the main group of bees on the hive into a nuc. I wasn't sure what to do about the smaller group on the fence so I smoked them gently to disperse them gradually with a queen clip ready in my hand. All the bees took to the air without me seeing a queen.
The few bees left on the side of the hive headed back towards the entrance. It was interesting to see that where they had been for a little over 24 hours there were small flakes of wax stuck to the hive - as you would expect with a swarm.
Still puzzled about this whole episode, I decided to have a quick look in the top hive. It was less crowded than before, obviously, and there were the remains of one torn down queen cell. There were no eggs or larvae and no sealed brood at all, apart from three sealed queen cells on a frame containing nectar. No other brood at all in the hive.
Mystified, I went back towards the house and noticed several followers, despite the bees having been very calm. I went into the greenhouse to put the camera in a safe place before I took off my bee suit. When I returned there were several bees flying around the entrance to the greenhouse. Looking inside, there were a few more in the roof, including a queen! I guess she must have escaped from the nuc or the bees on the fence and hitched a ride on me to the greenhouse. You can see she is relatively small, so new and either unmated or newly mated. I couldn't see that she would be much use in management of the hive so I removed her.
A further check today (22 June) shows that there are bees in the nuc but I doubt that they have a queen. I decided to reduce the three queen cells in the top hive to one but when I removed the first two they were empty. So I took out the third and that was empty as well! The bees in the bottom hive are just fine with seven frames of brood and no sign of mischief. I think my final move will be to unite the top and bottom hives and leave the old queen in charge. So right back to where we started.
I have found this a fascinating but completely puzzling episode. My main unanswered questions are:
1. Was the increasing bearding over a few days a sign of an imminent swarm or a coincidence?
2. Why did the swarm settle on its own hive?
3. Why were there two parts to the swarm (if that's what they were), coming out hours apart? Could they each have had a queen?
4. Why did the bees swarm leaving only three empty queen cells? Were they somehow fooled into thinking they were real? Or were they influenced by the smell of the queen downstairs? (This hive is no different from one with a Snelgrove board in that respect.)
5. Did I get it all completely wrong and this was just something to do with a mating flight?
Any comments will be most welcome.