The process of collecting a swarm can be quite simple -   I cut the twigs that the bees are on, and the swarm drops into a carefully placed box underneath.  The box is then inverted on a bed sheet on the ground and propped up so that the stragglers can find their way in. Bees communicate using chemical signals called pheromones. At this stage you often see bees at the entrance of the box fanning their wings to spread their pheromones to call the remaining bees into the box. Once they are all in, I tie up the bed sheet and pop the parcel in the van and then rehome them in a new hive  in one of my apiaries.