A very useful item in any apiary
In the U.K. a nucleus is defined as "a well balanced colony on between 3-5 B.S. brood combs". I wouldn't normally disagree with that, especially if it was offered for sale, but this is for my own use. Certainly many beekeepers wouldn't normally make up a nucleus of less than 3 frames, apart from perhaps short term to keep a queen laying for a few days, or to create temporary space in a brood box for some purpose, such as to make a colony queenless to start a frame of queen cells when using one of the "artificial" queen rearing methods.
The perception is it is too small and as it isn't found in books, it is not advised by teachers, demonstrators and lecturers.
They are only 2 frames for a short while after they are made up. If everything goes to plan they can expand very quickly. You need to understand why this happens at certain times, so you can manage it.
Some uses for a 2 Frame Nuc.
I have used these small nucs successfully for many years. If you don't have problems getting queens mated, especially with the first queen, they work very well. If the first queen fails they can be set back a lot. I find the addition of a comb of unsealed brood and another Q/C soon brings them back on track. If there is a nectar dearth they may need feeding, but that is the same with any small colony.
How I make up a 2 Frame Nuc.
Management of a 2 Frame Nuc.
These small nucs are often used for queen mating, so I place them at random in the apiary away from larger colonies, to prevent returning queens going into the wrong colonies. If they are close together, I face the entrances in opposite directions and make sure there is some sort of marker such as a tree, bush or post to help the returning queens find their own hive.
Depending on the time of day the nuc is made up, I normally check after a few hours flying to make sure they haven't lost too many bees. This is important, otherwise you can lose some unsealed brood, especially if it is on the periphery of the comb where it becomes abandoned. Don't forget when making up a nuc that bees on sealed brood are more likely to be older bees who have flown, so may return home.
As with any hive where queens are likely to be returning from mating, I don't usually inspect these nucs between 10.00am - 6.00pm
The management of these small nucs is quite easy, I treat them as a group together where I have developed a simple system. I start them in succession at different times of the summer, usually when I have a batch of Q/Cs, so I have them in different states. If I have a spare Q/C from a good colony, I will make one up. When established, I can easily increase or decrease the size by adding or removing frames of brood or food, or by changing places, so the stronger ones can provide flying bees for the weaker ones. Those that have just been made up in the same apiary can be put in the place of an established one. There are many things you can do, but of course you need to know what the bees will do in response to your actions.
If you don't know when the queen is likely to emerge, as when using a "natural" Q/C, then check 2-3 days after you have made the nuc up to cut out any emergency cells. If your queen has emerged there is no need to. Don't be frightened to have a quick look for her. I know it is frowned upon by some, but it will give you practice at looking for a virgin queen. Sometimes queens emerge with damaged wings and if you see it you can do something about it.
After 8-10 days it is often helpful to swap places with the two original frames, returning the nuc to a more natural state, i.e. food outside brood. If you aren't able to do this, but have given it enough food, there is no need to look at the nuc for a couple of weeks, when you can check to see if the queen is laying. At this point there is little brood to feed and brood is hungry, so they should have enough food from what you gave them.
Future management will depend on your own circumstances. If you wish to use it mainly for mating queens, then you can remove the queen when required and replace with a queen cell in the usual way. If you don't need to introduce the queen immediately then leave her there, she will be well looked after.
With my bees, a queen will lay up a standard B.S. brood comb in about 1½-2 days. This means that the box will be laid up in about a week or a shade less. There is little point leaving the queen there any longer, so I usually remove her and replace with a Q/C. In reasonable weather a queen is often laying 14-16 days after the Q/C is given. It takes around 6-7 days for the young queen to lay up most of the box, so she can be removed and replaced with another Q/C around 22-24 days after the previous one, but let's work on 28 to allow for poor conditions. At best we can assume we can work on a Q/C being inserted in the first week of each month May-August. In a poor summer or further north these times will be delayed, probably reducing the number of queens mated in a summer from 4 to 3.
As a frame of bees becomes 3 frames of bees when it emerges you will find short periods of rapid expansion, instead of steady increase. In general there is a rapid increase in adult bees 3-4 weeks after each queen starts to lay. This usually means that if the queen mates O.K. and there has been no manipulation of combs of brood the nuc will need moving into a full hive quickly, especially if there is a nectar flow, otherwise the second queen may have reduced laying space.
If I want more mating nucs I split them into another 2 frame nuc, giving it the same as previously, i.e. one frame of largely sealed brood and one of food, but leave them on the original site to collect the flying bees and move what is left a few feet away.
I usually have a stock of drawn combs which I prefer to use instead of foundation. One great benefit of drawn comb is that if the nuc is strong queens lay a comb very quickly, meaning that most of the brood is roughly the same age. This has a knock-on effect, so can be helpful on occasions.
I don't normally do any queen rearing later than mid August, but by that time I know what the state of the colonies is. They will not build up any more and if any are strong enough to go into winter on their own I leave them, otherwise I either unite several together, or to colonies where I wish to replace queens. I have a number of nuc boxes without floors. These I use on top of the standard nuc boxes, mainly for uniting. Colonies winter well in these and with a young queen are raring to go next spring.
This system works well most of the time, but if you get a failed mating early on you may have to add a frame of sealed brood or unite to another one. Once they have got to a reasonable size, perhaps 4-5 frames of bees it is much easier to put them right if you have a queen failure.
Some problems of a 2 Frame Nuc.
There are the problems you often get when using nuclei. There are extremes and they can happen quickly. Queen failure is an obvious one, but you can get that in any colony. In general the smaller the colony, the quicker it needs dealing with. Another Q/C and a frame of sealed brood works well.
In a week of good weather during a nectar flow, especially when there is no open brood, bees can fill the box up, so when the queen starts to lay there is nowhere for her to do so. Don't think that nuc's can't swarm! A week of poor weather, when there are several frames of unsealed brood, as you get soon after a queen starts to lay, and the nuc can be on the point of starvation.
It is advisable to fill boxes with combs and/or dummy boards. If the conditions are favourable you can have wild comb built and filled with brood or nectar very quickly.
Some of the benefits a 2 Frame Nuc.
I am not claiming this as an original idea because it has probably been used by others in many different ways, probably mainly as an emergency measure. I am the first person I know of to use 2 frame nucs as part of a management system and to the best of my knowledge the first to write about them. I really don't know why it isn't used more widely, as it is so simple. Since I have used it, several other beekeepers have done the same, one BKA now uses it as a cheap and simple way of making up nucs for beginners. There are a lot of options and many more than those I list above.