The 2x4 deep OH on our sunporch died out last year and i left it alone except to freeze the frames after it attracted a few moths. I also started spraying a little Swarm Commander in the vent weekly from a few weeks ago until recently.
Yesterday my wife texted me that there was a buzzing in there! I came home to find 30 +/- workers scrambling around in what I figure was the behavior of "measuring" the cavity described by researchers. It was super-windy yesterday so i was surprised. It's also been a bit cold. 37f this morning. Took a walk around the bee yard and, sure enough, there they were. A good size swarm clustered on the side of a tree about 15ft up. I'm going to let them decide whether or not to move in. One little half a spritz of Swarm Commander for luck. Update to follow...hoping to report good news later today.