If the bees have only just arrived, then a few drops of Bee-Go will persuade them to move on in a hurry. See an earlier posting about Bee Go for more on that subject. This post is about extracting established colonies.
You will need special equipment, either an adapted nucleus box or a specially made box. I have one of each and both are on loan to friends at the moment. You need to do it in lots of little stages. I tell people that it could take 6 weeks (to allow for complications and slippage) but usually it is less than that.
First locate the entrance. Is it the only one? Block off all others. Abut the box to the entrance, making a bee-tight seal around it with duct tape or similar. Often this isn’t easy as it will probably be half way up a wall and not very accessible. On a couple of occasions the owner arranged scaffolding especially for the purpose and on another, the bees being in the roof of a manor house, there was scaffolding already in place for building operations.
In the current situations, one is above a beam over the entrance to a barn. My apprentice, Zoe, built a shelf there 3 or 4 years ago to remove the bees using my kit and so acquired her first bees. Now the cavity has been re-occupied as she forgot to fill the cavity with foam. As she also forgot to remove the shelf, we just put the box back.
The other is high up in a house wall. The owner is making alterations and has long ladders and is happy to build a platform to fit the box and fill in any alternative entrances. My friend, Liz, who lives not far away and will do the job, isn’t good with heights and so will probably direct operations from the ground, maybe with the aid of a mirror. That one has just thrown a swarm so we will wait a while until the new queen has been mated and is laying. Liz, maybe using binoculars, will look out for increased pollen gathering as a sign that they have new babies to feed.
Stage two is to get the bees used to flying through the new entrance you have provided outside their habitual one as it will look different to them. Leave the box open at first. After a day or three, put the lid on the box so the bees will have to use the ‘official’ entrance. Sometime I make it more obvious with a splash of colour.
When they’ve got used to that, you go along with a frame with drawn comb and maybe (there are as many variables as there walled colonies) another with some older brood, too old to turn into queen cells. Fit Porter escapes into the slots you have prepared. I always have 2 adjacent holes as insurance in case one of the Porter escapes gets blocked.
Bees now leaving their colony in the wall can’t get back in so, instead, they cluster in the box outside, the combs you have provided giving them somewhere to cluster and the brood to make it seem homely, giving off the right sort of pheromones. This may reduce the chances of laying workers arising.
What happens inside the wall? Suddenly there is no income. Ok they have loads of stores and can survive for a while, but there’s no water coming in to dilute the honey (which is ‘hard tack’ to them) and, in summer, little condensation they can use. So the queen will quickly go off lay. There’s still over 3 weeks’ worth of brood to emerge and they will continue to care for it as best they can, but young bees will continually be leaving the wall to join their sisters outside.
The brood you have provided outside will soon be sealed and some emerging. Add another comb with older, open brood. It is very likely that, at some stage in the proceedings, the queen, possibly attracted by the pheromonal ‘noise’ outside will, herself, exit and join the mob, resuming her laying out there. So keep an eye out for her or her eggs at each visit.
If after a month the queen hasn’t emerged then presume her dead. You can then add a queen from elsewhere, or a protected queen cell, or a comb with eggs and young larvae from your favourite hive so they can rear one for themselves.
When you’re sure that every bee that can emerge from within the wall has done so, remove the Porter escapes and replace them with queen excluder. This enables the bees outside (but not the queen!) to enter their old home and rob it of any stores.
Eventually you decide that the job’s done and take your box of bees away to a site a couple of miles or more away. Tell the householder that bees always go where bees have been before and that if he doesn’t fill the cavity with squirty foam or seal all gaps the exercise will have to be repeated in a year or two.