What to do with an empty nuc?

I got my nucs last Thursday and my hives are doing well. I watched them yesterday. It was warm and hundreds of bees were returning from their foraging with legs full of pollen, some yellow and some red. The yellow are from forsythia and the red is from a blooming magnolia tree.

Here are the two stacked nucs as I received them, just before I moved the bees into the hives. They are plastic corrugated board folded up to take five deep frames.

I hosed out the empty nucs and put five frames in one of them. I bought some bee pheromone on eBay. I now have the nuc over at my brother’s house in a secluded corner. The odds are 100 to one against me catching a swarm, but I have the nuc and the pheromone only costs $2. The nectar flow has started and if any colony within a mile or so of this swarms, I might just catch it.