The number of bees in a honeybee colony ranges depending on the season. Sometime in the middle of the honey flow (April-July or so here in WV) a good colony will have somewhere around 60,000-80,000 bees in it. In the middle of winter, the colony will only have 20,000 or so bees. Typically, the more bees there are in a colony, the more honey they can make. So, sometime around the end of January or the beginning of February, the queen starts to ramp up her egg production and the colony starts to grow in number to get ready for Spring.
Most queens are egg-laying machines, capable of laying up to 2000 eggs per day. When a hive gets too full of bees, spring fever hits and the colony makes preparation to swarm. Swarming is a natural reaction to over-crowding and is the typical way the species propagates. The old queen and a bunch of workers (half give or take) will leave the hive and find a new location. Prior to leaving, the workers make several queen cells (they feed fertilized eggs/larvae the proper amount of royal jelly and the larvae will turn into a queen) so the remaining colony will still have a queen after the swarm leaves.
An observant beekeeper will watch for the Spring build-up and may consider splitting a colony that grows too big. Swarms are a lot of fun to watch and to catch, but a beekeeper runs the risk of irritating his neighbors or losing the colony to the wilds. I prefer to split a colony before it gets the urge to swarm so I can retain all of my bees. So, last night I split a few of my “booming” colonies. I simply take 3-5 frames with a mixture of bees, brood, eggs, pollen and honey and move them to a different hive box. I make sure to leave the queen in the original location. The original colony will remain strong as the queen finds she has lots of room to lay more eggs (in the empty frames I put in place of the ones I removed) and the colony will make lots of honey.
The new colony will feed royal jelly to a number of eggs (in essence, making their own little swarm condition without actually flying off) and end up with a queen in 3 weeks (if all goes well). The split probably won’t make honey this season as they have to hatch a queen and wait for her to get to full egg-laying capacity, but they should be strong going into the Fall.
I was able to find a few queen cells in the original hives so I took them and put them in the splits so I know there is a queen already pretty far along in the development process. These splits have an even better chance of having a good queen and growing rapidly since they won’t suffer the 3 week delay to make a new queen from scratch.
I make splits every year and have great luck at it. I will probably re-queen these splits later this season or maybe next spring as I want to maintain genetic diversity, but in the short term, I now have more colonies than I did 2 days ago and I will almost assuredly make more honey than I otherwise would have made. Honeybees are so cool!