Back to the Business of Bee Removal -- HELP!

Tereza from Gaston wrote to ask if our attempt to remove a swarm of honey bees from our barn wall using a product called Bee Dun had worked. Honestly, it did not. As Paul Harvey would say, here's the rest of the story.

You may recall that we consulted with a couple of local bee keepers before drizzling Bee Dun, an all natural herbal product designed to encourage bees to leave the hive, into the wall where the swarm had taken up residence. At first, the Bee Dun appeared to be working.

Lots of bees came out of the wall, clustering on the barn exterior. Unfortunately, the queen wasn't among them. Day after day, I upped the dose of Bee Dun and after going through two bottles of the stuff, part of the swarm seemed to develop some sort of an immunity. Well, it was worth a try!

So, we are back to pondering how to remove the bees in our barn wall. Tereza, who is facing a similar situation, is considering a trap out.

Okay, all you bee aficionados... Tereza and I could really use your help. What is the best way to safely remove and preserve an unwanted honey bee swarm, one that's taken up residence inside a wall?