Capturing a swarm of bees is probably the least expensive way to expand your apiary. In the spring, bees reproduce by swarming. An existing hive will raise new queens that will supersede the old queen. The old queen will leave the hive and take with her some of the bees to form a new colony. At this time, a beekeeper can set a trap baited with honeycomb and a pheromone to attract the bees to the trap. The beekeeper can then move the bees to a permanent home. A small 5-frame "nuc" hive makes an effective and reusable swarm trap.
Purchase a 5-frame nuc hive from any of the reputable beekeeping equipment companies. Along with the hive, purchase a vial of Nasonov pheremone and an entrance reducer for the hive.
Remove a frame with existing honey comb from an active bee hive. Ensure that there is no brood comb with baby bees in the frame and remove all of the adult bees from the frame. Open the nuc hive and remove the center frame and swap it with the frame with the honey comb.
Open the vial of Nasonov pheromone and drop some into the hive. Be careful not to get the pheromone on your hands as this can transfer the scent to other areas, making the trap less effective. The pheromone lasts up to one year.
Close the hive lid and position the entrance reducer to create an entrance at the bottom of the hive that is about 2 inches across. Scout bees looking for a new home appreciate smaller entrances they can easily defend.
Place the nuc hive securely in a tree or other high place around 10 to 12 feet off the ground. Check the trap regularly for any activity to see if it is inhabited. If so, wait until evening when the bees are all in the trap. Then, plug the entrance with a rag and remove the trap. Move the frames within the nuc to a new empty hive the following day.