One big advantage of honey bee culture is the ability of the beekeeper to divide a colony into smaller units. There are many ways to “split” a colony of honey bees with relatively little effort. This has become a more-used strategy under current beekeeping conditions, beyond the traditional reason, preempting a colony casting a swarm. It provides a way to keep smaller colonies, nuclei (“nucs”) in reserve to replace larger units that have suffered population loss through stress or pesticide poisoning.
It’s relatively easy to divide the brood that is present, making two or more new colonies, then called nuclei or simply “nucs.” The difficult part is ensuring that each resultant unit has an adequate population of adults. This is usually accomplished by putting more adults into the division that is moved to a new location, important because if not, many will fly back to their old nest and the new unit will then be at more risk of perishing than the parent. As a corollary, leaving the weaker half of the split colony at the old location will result in a larger population. Older foraging bees from the relocated part will fly back to their original location.
Anywhere from four to six frames of sealed brood are usually recommended to make new divides. Brood close to emerging can be placed in units where adult populations are low, because fewer nurse bees are needed, unless the nights are very cold and there is risk that it will chill and die. Emergence of this brood shortens the time before the new divide is at full strength.
If cold nights are a problem, a new divide can be established over an existing colony. It should be separated by a double screen and have a reduced entrance to the rear of the colony on which it is located. This way, heat from the colony below will help keep the brood in the new division warm and foraging bees will be less likely to enter the stronger bottom colony. When the top colony (new divide) is subsequently moved, however, the balance of bees could be upset. Those adults used to the location of the original colony will invariably be lost unless the colony is moved over two miles away.
In the final analysis, success in making divides depends on the beekeeper’s judgement and experience. See a number of ways to make splits as found on the World Wide Web, as well as a discussion on this and queen rearing in a sustainable apiary. Something called a “walkaway split” is often used simply as a re-queening method. All this falls under the rubric of increasing colony count in the apiary. Mistakes will be made by even the most experienced operator in some years. However, in cases where bees are likely to swarm anyway, divisions becomes a good way to use the honey bee’s reproductive instinct to the beekeeper’s advantage.
A key to making splits is to ensure replacement queens are available to the new units. It is possible simply to allow a new divide to rear its own queen if the proper-aged larvae are available, but this can be extremely risky and may result in failure of the new unit. Using nuclei (small colonies) to rear queens is also an important skill. See a number of ways to make a split suggested on youtube.com.