Does swarm prep suppress emergency queens?

Not having one-day-old larvae suppresses emergency queen production! Give that one a mated queen in a Laidlaw cage pronto!

Only other thing is maybe they have a queen who is holding up on laying for a while - how are conditions? Do they have pollen stores? Without pollen, many queens will not lay eggs, as the brood needs the protein in their royal jelly. Many a beek interprets this and queen failure. It is probably better interpreted as beekeeper failure!

Check them carefully for a queen, run a queenless test. Put a caged, mated queen on top of the frames. If they flock to her and adore her and feed her, they are queenless. If they ignore her or form an attack ball, they have a queen. If they are queenless, add that mated queen under a Laidlaw push-in queen introduction cage.

I would give them a frame of young brood first. If that frame has no cells in 4-5 days you almost certainly already have a queen.

I have done this test when I thought it came out wrong for some reason - but it never actually WAS wrong. At least not for me. It can save your expensive store bought queen from being killed though.

Also just the act of giving a hive a frame of open brood every few days will prop it up for a pretty long time and almost always results in a net positive for your apiary as a whole.

One of those cases where no answer seems quite right. They did have day old after queen removed for several days as they went from eggs to larva. Most likely I missed something, queen or used cell.
Been inspecting too much for new queen time period. Will walk away and add eggs/brood this weekend and wait.

If you are trying to save money on queens, by all means give them open brood. The cost? It takes a lot longer before the new queen is laying a strong brood pattern. This costs the colony precious weeks of nectar and pollen flow in the spring, although it is almost solstice, now.

A mated, laying queen - either combining with an over-wintered nuc' OR "store bought" gets them back on line and making honey, bees, pollinating, and all that good stuff in a hurry. The "store bought" queen option is best introduced in a Laidlaw queen introduction cage, a darn-near guarantee of acceptance.

Brother's hives ,his rules. He does not want more than the 3 he has. Gave me frames to start nucs with store bought. Originally was going to split 2 of his with excluder, start QCs and mate then recombine back to the 3. Bees were already moving ahead with their own plans (backfilled and few eggs) so old queens got moved as well.
It was when we went back to look for QCs that we found none started in one of the hives. Probably moved early swarm cells out to new nuc with old queen. Will check for those next trip in.