I found these supersedure cells, sure sign of a queenless beehive, yesterday. Supersedure cells are a beehive's way of raising an emergency queen. Something has happened to the queen, either it died, or the workers killed it because it was injured or not laying well, and the honeybees are raising a new queen. There were no signs of freshly laid eggs in this hive, and very little capped brood.
Supersedure cells are different than swarm cells. Swarm cells are queen cells that the hive is raising to create a new queen to take over the hive after the hive swarms. When a hive swarms, the current mated queen leaves with the swarm, leaving the new queen raised from the swarm cells to take over.
This hive had already swarmed, and I was thinking the new queen probably wasn't well mated, considering we only have two hives in the yard here, and there is only one other hive nearby of Italians that I know of – there are probably feral hives nearby as well.
How do bees raise a new queen? They take some freshly laid eggs, usually 1-3 days old, and place them in these enlarged queen cells, and feed the larvae a diet of royal jelly. They don't feed these larvae anything else, and the 100% royal jelly diet causes them to develop into queens rather than workers.
I happen to have just raised a new queen in my queen nuc, so I pulled out the frames with the supersedure cells on them, placed them in a nuc with some honey frame and workers, to make new queens.
I then took the nuc with the mated queen I just raised, and did a hive combine of the queenless hive and the mated queen nuc. I shot some video and we'll be posting a video of that soon.
Added: Beekeeping nomenclature can be vague and confusing, because there is no one beekeeping terminology authority, here is a description of supersedure cells from my favorite beekeeper, Rusty, of HoneyBeeSuite.com :
A cell hanging off the middle of the frame somewhere is usually a supersedure or “emergency” queen cell. A cell hanging off the bottom of a frame is usually a swarm cell.
Supersedure cells are often begun after the eggs are laid. The bees, knowing they need to replace the queen, begin feeding royal jelly to a young larva they have selected. They build a supersedure cell around this larva (or several larvae) and it hangs down from the face of the comb. Swarm cells, however, are built in preparation for swarming and are not intended to replace the queen, but to raise a second queen. This way, there will be a queen for the part that swarms and a queen for the part that stays.