Swarm observation

This has been a great year for swarms - I've been called for several already. In addition my observation hive swarmed up into a nearby tree and was captured and installed in a new box. Not to be outdone, the remaining observation hive swarmed again yesterday on the 4th of July. I knew they were up to something because I could hear a queen/queens piping all the night before and I finally was able to spot a massive swarm cell in the hive. When I lifted the cover to look, they all absolutely looked guilty - like "we ain't doing nothing". 9:30 the next morning I happened to look out and see a cloud of bees flying around a pine tree in my yard. I ran out and watched them swirl around me and then coalesce onto a branch about fifteen feet in the air. I put down a plastic drop cloth, brought out a nuc box with frames and got my trusty five gallon pail on an extendable pole and in no time they were all settling into the box. I put them in the apiary and went off for beer and ribs. When I got home I noticed that unlike other past swarms, a significant portion of these were hanging on the outside of the box and I began to suspect their brush with freedom had been too brief and there was a risk that they might head out again. I thought about what to do and then the obvious answer appeared. I dug into one of my larger hives and found a frame with honey, pollen and milk brood. I found the queen on another frame so I could safely take this frame. I opened the swarm's box and removed one of the empty frames and put this frame of brood in. Within half an hour all the bees were inside and today I see they are flying normally and collecting nectar and pollen. I imagine they are astounded that their queen has already produced brood but that brood pheromone is clearly a potent behavioral control. I may think of doing that with future swarms as well - no question of settling down once they smell brood.