On the recent subject of swarm prevention and splits,  I am a fan of making
nucs (small splits) early in the spring (first week of April for us in
Maryland).   These small splits are given 4 medium frames of brood (I run an
all medium operation), and a new queen.   These nucs are later sold for $40
each, with a good market.
 
The main colonies benefit from the nuc as a swarm prevention measure, local
beekeepers get new colonies, and I get some cash for my efforts.
 
W. G. Miller
Gaithersburg, MD