I have a nuc that has really taken off, and I just found some swarm cells. Whats the best procedure to split a 5 frame nuc. I don't really have any frames from other hives to spare. I have another empty nuc box and an empty 10 frame deep available to use for split, just no comb.
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5 frame nuc is minimum size hive. You cannot split it. It will ruin your hives.
If that size hive is trying to swarm, it is perhaps too full of honey or sugar syrup or it has not enough space to expanding bee number.
It wants to change the queen perhaps .
You should report
how much frames filled with bees
how much brood
how much honey and pollen
how much free cells where to lay or store nectar
how much free frames what bees do not uccupye/cover
If it is full of bees, you can place a frame of honey with a frame of brood with a queen cell in one section of a queen castle and raise up a queen. Just make sure you keep a syrup jar on them.
But in your case just put them in the 10 frame box and hope for the best.