I was called today to an unusual situation: a swarm on the pavement outside a house on a fairly busy street. When I arrived the bees were like a splat on the ground. They were next to a low Privet hedge, so I suppose that they'd fallen out of that.
I spoke to the house owner and got a box. This covered the splat while I went for my swarm catching equipment. When I returned they had started to cluster on a flap beneath the box. I had brought a larger box so I carefully placed small box with bees inside the big box.