Allot of people ask on how to extract a colony out of a tree or whatever have you.

Getting a colony out of a tree can get very tricky and cumbersome if you don't want the tree or wall to cut down.

Cutting down and open carefully would be the easiest but no guarantee that you'll get the queen out alive.

This is how I would approach it,...screw some angle brackets onto the tree and set a hive box up with foundation [on top level of hive in the tree] or if you have a frame or two of new brood from another hive, bees want to tend the brood so you'll have some of the bees going into the box right away and stay,...how?
Seal off all entrance from the tree, except one, the highest on the hollow, there you attach a hose/tube, perhaps staple fist a screen, shaped into a funnel, onto the tree, funnel into the hose going into the bottom board of new hive box, drill hole first, perhaps using something like a one inch rubber hose.

All bees will have to go through the hive entrance, going and coming, hopefully the queen will go up when the tree hive gets filled up, [in the tree] bees and queen love to go up, never funnel downward. Check one's in a while, about one's a week and see if you have new eggs/brood, this will tell you that you have the queen, then undo the hose, perhaps move the box a bit, and smoke out all bees out of the tree and shut close.

You'll have some angry bees /swarm around and looking for the home, eventually they settle down and go into the hive box.

Brood in the old hive will die out,...open up about Sept. and let bees rob out the honey in the tree, this can take a couple of weeks, when no activity, seal up again, otherwise a new colony will move in again next year.

You can open briefly in spring again to clean out some more if needed.

Timing is important, do it in early summer when the colony is expanding, don't do it in fall.

I know, easier said then done.