To add to Allan's excellent post- I have been splitting every
year and not bought queens or raised my own by grafting. I have
found the easiest way to split is wait till the bees are in both
boxes, smoke the upper box heavily to drive the queen down to the
lower box. Remove the lower box to a new hive stand. So now you
have the field bees supporting the new queens hive and the old
queen will continue to lay and replenish the field bees lost in
the split fairly quickly.
Last year I tried splitting by leaving the queenless upper on the
hive with a double screen between. It worked. It also allows
combining the two for a two queen hive, combining if there is no
queen produced and splitting as I use to, with the new queen in
the old location. A little more work, but more flexibility.
Bill T
Bath, ME