The concept of an Unlimited Brood Nest (hereafter called ULBN) is in contrast with the normal practice of limiting the queen and the brood nest to a specific area (usually one deep or two deeps). It seems to mean different things to different people. To some it's just three deeps with an excluder on top. To some it's not limiting the queen at all. Basically anyone not using an excluder is running an ULBN since the queen can lay where she likes, but usually it also involves extra stores for building up in the spring.
The old ABC & XYZ of Beeculture books call running a hive with three deeps for the brood nest a "food chamber". At least the third box is. The idea was that the bees had more resources in the spring to rear brood so they would expand more sooner. This is still the same concept of more boxes.
In order to run one effectively you really need (in my opinion) to have all the same sized frames in a hive so you can encourage the queen to lay in multiple boxes and you need to not use an excluder. If you use an excluder how is it unlimited?
Dee Lusby's manipulation she calls "pyramiding up", is a way of getting the bees to move into multiple boxes. Basically she takes some brood from the brood nest (two or three frames) and moves it up to the next box so the bees will spread out the brood nest. This often gets the queen moving between several boxes laying. Walt Wright's Checkerboarding also encourages the queen to move when she wants and the bees to open up space for the queen to lay. Whatever method you use, the concept is to get them to expand the brood nest. Putting empty frames in the brood nest also encourages them to expand the brood nest. You can do this horizontally or, if there is not enough room, you can do this while moving some of the brood up a box, but then you're "pyramiding up" again. Bees often hesitate to move into more than one box. By moving brood to other boxes you speed up this indecision. You need to do this judiciously. The bees have to have enough nurse bees to cover all the brood when you do this.
So, the short version is that ULBN usually involves three concepts:
o Not limiting the brood nest to a small area.
o Getting the queen to lay in more boxes.
o Leaving the bees more stores to rear brood on in the spring.
______________________________________
Michael Bush
Copyright 2006 by Michael Bush