Currently, I do no splits. Instead, I let those hives that have excess
population swarm naturally. I then collect the swarms as the sole means
of hive increase.  . . . The downside is the intense labor needed to
collect and hive up the swarms especially in mid May.

  The swarms that you do not catch may come back to haunt you as they
will take some Varroa mites with them.  In a period of time 6 months to
a year without treatment this swarm will probably die out from Varroa
and your colonies will rob out this swarm and carry home a large
resevoir of Varroa mites.  I have seen strong colonies at the beginning
of July (Apistan strips just removed) dead in October. The bottom board
turned red from Varroa mites.   This case was due to bee havers not
medicating and colonies in the area crashing.  The same results could
happen with a failing swarm.

Ken Eastman
Monaca, PA