Cool looking swarm. This was the exact visual I had, when you described them to me and I had this thought in my head which now after seeing your picture most likely would have worked.
Seems they are pretty much on one side of the fence right? Well, next time, if you happen to have a piece of plywood with you, you could place it against the back side of the fence, then smack it a good hard lick. They should drop right in the catch box.
Let those bees do anything they choose, but don't let them step on your blue suede shoes!