Some of the most useful ideas in beekeeping never make it into the textbooks. Peak Queencell Number, or PQN, is one of them. The theory comes from Roger Patterson, and once you’ve read his explanation you’ll start noticing it in your own colonies.
What is PQN?
When a colony prepares to swarm, it builds queen cells over roughly six or seven days. How many it builds varies a lot from colony to colony. Most will produce somewhere between 6 and 30, but some go far beyond that. Roger once helped a beekeeper cut 119 queen cells out of a colony that had swarmed.
What Roger noticed is that each colony tends to stick to its own number. A colony that builds 8 to 10 cells will build around the same next time, and one that builds 25 to 30 will do the same again. It seems to be a figure the colony is comfortable with. The count is taken at the point of swarming, not a few days earlier when some of the cells haven’t been started yet.
Roger has only found the idea described in Beowulf Cooper’s The Honeybees of the British Isles, with a brief mention in Richard Smailes’ Raise Your Own Queens by the Punched Cell Method. In his experience it holds true more often than not, and he’s puzzled that it isn’t better known. It certainly matters in other areas of beekeeping.
PQN and swarminess
Roger believes a colony’s swarminess is directly linked to its PQN. The more queen cells a colony builds, the swarmier it is. Fewer cells, less swarmy. He uses this when choosing queen cells or worker larvae for queen rearing. He’s happy to take cells from a colony with a PQN of 10 to 12, but anything higher only gets used if there’s nothing else available.
Emergency cells
Remove a queen and the bees will start building emergency cells over the following few days. The total usually ends up close to that colony’s PQN. Cut out more than a few, and the colony will often build replacements to bring the number back up, provided there are worker larvae young enough to use.
Raising queens
This is where PQN has real practical consequences. When queen cells are raised artificially, by grafting or the cell punch method, colonies tend to be reluctant to raise more than their PQN. A lot of queen rearers don’t realise this, particularly small-scale beekeepers.
Roger only puts a single bar of 10 larvae into a cell-raising colony. He has tried two bars, 20 larvae in all, but the bees don’t seem to accept more than about 10 to 12. He’s perfectly content with that. The catch is that if you’re selecting for less swarmy bees, you won’t be able to raise the huge batches of queen cells you see in books and online. Pictures showing 60 or so cells are common, but they’re probably from other countries, and Roger suspects the colonies building them are very swarmy indeed.
It’s a simple idea, and a useful one. Next time a colony swarms, count the cells. It might tell you more about those bees than you’d expect.