A swarm is either a prime swarm headed by a mated queen probably at least a year old, or a cast headed by a virgin queen that will need to get mated before commencing egg laying. A cast is likely to be smaller than a prime swarm. A prime swarm might supercede its queen in the autumn. You will receive it in a nuc box, polynuc, skep or cardboard box, and it will need to be transferred into your hive. This is done in the evening, and can be done in the traditional and wonderful method of laying a sheet on a ramp leading up to the entrance of the hive, tipping the bees out on to the sheet and watching them walk up to the entrance. If you are lucky, you will see the queen among them and, once she is in you are home and dry. Usually they will not all be inside by dark, but they will find their way in eventually.
They can be shaken into the hive after removing the roof, crownboard and a couple of frames in the middle of the brood box to make room. After the bees are in the brood box, close up the frames and the hive. Always hive on to frames of clean foundation Do not feed for 48 hours, then syrup made up with granulated sugar to draw wax, normally 1:1 but 2:1 is sometimes recommended. If possible get the swarm established in a quarantine apiary other than your usual one until the colony has sealed brood when it should be checked for brood disease before returning it to your usual apiary. Be mindful that your quarantine apiary might be close to someone else’s bees. While the swarm is broodless, this is an opportunity to treat it for varroa either with oxalic acid or Apiguard.
Expand the hive as the colony develops.