The Influence of Cell Size, Part 1
The Bee World – January, 1933 – Pages 37-41
THE INFLUENCE OF CELL SIZE.
By Prof. U. BAUDOUX, Rucher-ecole experimental de Tervueren-lez- Bruxelles. Belgium.
In intensive bee-culture, the question of cell size is of great importance. It is inseparable from those of race-selection and of the improvement of the capacity for egg-laying and accumulating stores.
The end proposed is magnificent: To rear bees of extraordinary vigour, able to forage over a more extended flight-radius and to visit a multitude of flowers the nectar of which is, at present, out of reach of their tongues. The tongue of the bee is, indeed, the essential organ which we must develop, by selection first, and then by rearing the bees in large cells; for it is plain that all the organs will participate in any enlargement of the body of the bee.
About 1891, foundation with cells 920 to the sq. dm. was introduced into our country. Beekeepers all adopted this size of cell. The experts of that time believed that it was advantageous to produce as many bees as possible on the least possible surface of comb. Thus there was a premature narrowing of the cells, and at the end of a few years the bees were miserable specimens.
It was then that, to combat so harmful a tendency, I published an article in Progres Apicole (June 1893) advocating the use of larger cells, as a result of experiments duly described. I had experimented up to the limit of 750 cells per sq. dm. These sizes of cells were obtained by stretching foundation. Mr. Auguste Mees subsequently made them by stretching the sheets as they came off the cylinders, in 1893 to 1895.
In November 1895, at my suggestion and after I had reported on these facts to the Assemblee Federale, this body decided to give an order on behalf of its members to that manufacturer who would undertake to use a special machine (which would give perfectly hexagonal bases), for foundation with 750 cells to the sq. dm. It was then that the first machine with 750 cells per sq. dm. appeared; Mr. Mees ordering it in response to this desire.
The bees will not build more drone cells on the sheets of foundation thus obtained, than they do on foundation with small impressions. Moreover, if bees want to rear drones, they will not fail to do so, even if you give them foundation with 900 cells per. sq. dm.
[Note. A sq. dm. is almost exactly 15-1/2 sq. inches. The numbers per sq. dm. must therefore be divided by 15.5 to give the number per sq. inch. Corresponding figures are: 930, 60; 852, 55; 775, 50; 697, 45; 620, 40; 465, 30. The count is for both sides of the comb.-Tr.]
The way was thus mapped out; and the results obtained were always satisfactory. But, unfortunately, one cannot please everyone. A long and underhand campaign was started by people without much experience against this idea of enlarging the cells. When conditions were equal, however, my crops were always larger than those of my neighbours. No one is so deaf as he that will not hear!
Encouraged by my experiences, I wished to do still better – to go to the bounds of possibility. But, to carry out my idea, I was in want (as in 1891) of the most important item – a machine which would give me larger cells still; and, to possess it, I had first to find out what point I ought to stop.
I therefore again proceeded by stretching foundation. Now, however, I was working with cells already enlarged; and any irregular cells would soon have been used for the rearing of drones. It was therefore necessary to work accurately. I invented a stretcher which gave me the number of cells I desired. It consists of a thick sheet of inclia rubber and a thin sheet of para, both held in a long clamp. The sheet of foundation, warmed, is placed between these; and, being rolled up, is drawn out longer. The operation is then repeated in the other direction. In this way, I was able to obtain sheets having only 741, 730 and even 675 cells per sq. dm.
Towards the end of 1927 appeared the new machine, giving 700 cells per sq. dm. (also made by M. Joseph Mees, who thus perpetuated the traditions of his firm).
Just as the 750 machine sometimes gives 736, so the 700 machine sometimes gives 685. Those who are used to such work know how that slight differences are inevitable.
For the last five years, I have been replacing all defective combs in my experimental apiary at Tervueren with 700 foundation; and all new colonies are set up on 685. This year I placed some swarms on 675. This apiary is accessible to all. It is the instruction apiary, where the official practical and theoretical lectures are given. It is visited annually by hundreds of beekeepers, by parties from Associations coming specially for an excursion, by bee-experts, by sceptics; yet all these people go away convinced. Moreover, the use of 700 foundation is nowadays frequent in Belgium and even in the neighbouring countries: the more timorous use 750. Progress is slow, but nothing stops it.
To convince the more pessimistic, I reared bees on 950. I wished to show how the bee reared in a small cell degenerates, whether the smallness results from the age of the comb or from any other cause. Bees reared in 950 combs are so small that the most sceptical have to confess that the following principle is justified: – The size of the bee is correlated with the capacity of the cell. Small cell, small bee; big cell, big bee. And the size remains the same during the whole of the bee’s life.
The drone reared in a worker cell is small and puny. I shall show later that, when reared in a larger cell, he reaches a formidable size.
Those who contradict the principle cited above are people who want to say something in spite of their ignorance and their lack of observation.
In order to keep a rigorous check on the results obtained, I was obliged to invent: –
The thoraxmeter, either with slide or dial (Figs 1, 4); the automatic glossometer, with dial and large fluid surface (Fig. 2); and the sacmeter, in which the honey taken by a group of bees is indicated by a capillary tube, easy to read off, outside the apparatus (Fig. 3). I shall give, in a future article, the results obtained with these instruments, each of which has been the subject of a thorough and most interesting study. Here I will only state the few essential points needed to make all clear to the reader. I take the liberty of giving, with some measurements of cells, the size of some bees from the Belgian Congo. These confirm the other results.
|No. of cells per
|Origin of the Bees.
|Space in mm. through which bees pass:
Native or Italian
As can be seen, the bees reared in cells of one size are not all of the same dimensions. For example, the 850 lot. Some of these pass through 3.8 mm., most of them through 3.9 mm., the largest through 4.0 mm. But, if the size of gauge through which the “850s” can pass is placed at the entrance of the “700s,” not one bee of this size could pass through.
Whence the differences of dimensions of bees from the same size of cell? Probably from their individual constitution, or from an unequal distribution of food. These differences occur, no matter what the size of cell.
The automatic glossometer has revealed many unsuspected things. The tongue of the bees gets longer by 0.5 mm. for each 50 cells less per sq. dm. of comb. Thus, selected bees from 750 comb have tongues of 7.7 mm. – a fact confirmed several times. The same colony was placed on 700 combs and examined two months later. The tongues were then 8.2 mm.; this measurement also was confirmed several times. There is always an advantage with the large cells. The experiments related in L’Apiculture Belge were made elsewhere, with conclusive results. The measuring instrument has a float and is of an admirable sensitiveness. I can measure to 1/20th mm.; it shows the useful effect of tongue length.
The sacmeter will be an infallible instrument of measurement for use on a group of bees. I am awaiting the results of fresh tests before publishing the measurements. It has been found that the sacs of bees reared in 685 are much larger. The figures will be checked in some forthcoming experiments. The wings are 1 mm. longer than those of bees reared in 850 comb.
Whatever people may say, Italian bees build, in their native land, the same size of cell as our native bees. I have received natural combs from Italy, and ascertained that the stories of combs with 764 cells per sq. dm. are – well, stories! There are people who will deny plain facts and who will at the same time accept other statements as gospel truth. I have measured 51.7 and 53.5 mm. per ten cells, just as with our native bees. I have made a longer investigation of this subject, which I will submit later on.
The influence of cell capacity is real, and no possible test has been neglected that might aid in making sure of this. All these matters have been set forth clearly, and beekeepers are now in possession of the data which have cost me much time, work, and above all patience to bring to a successful issue. They will profit by using the largest cells possible. The combs are drawn out more quickly, they are utilisable for longer in the brood-nest and they are easier to extract.
It might be thought that since a larger bee has been obtained, there remains nothing to be done. It would, however, be flying in the face of all progress to put “perfect” at the end of any task. One cannot stop upon the road.
In spite of the results attained, I am asked: Will it be possible to fix naturally a race of large bees? To that I reply this should be a task for us all for it is difficult to eliminate from one’s neighbourhood all the elements harmful to such an enterprise. Nevertheless, the good seed spreads, and it is always possible to improve one’s district by “radiation.” All my work is directed toward that end.
In the first place, do the bees reared in 700 combs possess dimensions rendering them capable of building larger cells? To that I reply; Yes. They build worker cells of 736 and drone cells of 470, instead of 85O and 530. I have had occasion to confirm these facts many times already, but I was determined to make a public experiment in the presence of expert beekeepers. Two skeps (cloches) were populated with bees reared in combs with 700 cells per sq. dm., and also a nucleus hive with empty frames. A little melted wax served as guides. The same beekeepers, at a meeting called specially later, were able to confirm the measurements given above. The centre to centre measurement was carefully tested; it was 36 mm. I shall return to this presently.
There is thus an enormous advantage, and that for a first generation from parents reared in 850 comb. But what will happen when the bees participate in the heredity of queens reared by “700″ bees (therefore larger) and of drones reared in cells 470 per sq. dm.? I think that the bees resulting from these crosses (which will necessarily be made in the future) will have even more aptitude for maintaining larger cells and a larger race.
Consider the size of the drones reared in worker cells (5 mm.), ordinary drone cells (5.5 mm.), and cells of 470 comb (6 mm.). At the first glance the difference of size and of length of these drones (on pins at the apiary for demonstration purposes) is striking. As with the bees, their large size, once acquired, is there for life. These 6 mm. thorax drones are show objects. They will serve to extend selected strains and to maintain a naturally large race. It will be desirable to measure the choice drones and to eliminate undersized ones. There is some work there for investigators; any results sent to me will always be welcome.
The two colonies in skeps enabled me to determine that the worker combs (empty brood combs) were 22.8 mm. thick, and the drone combs 29 mm. The spacing of frames from centre-to-centre is 36 mm. Consequently, I conclude that a centre-to-centre measure of 39 mm. is necessary for convenient manipulation of the hive and to avert congestion of the spaces by the large bees.
This question of cell size is necessarily linked with that of hive capacity. Supported by the reasoning of Dadant, Voirnot, Layens, etc ., and in order to avoid entering upon a multitude of controversial questions, I shall state, as they do: the brood-nest ought to contain about 63,000 cells for laying in, in addition to the space needed for the rest of the bees’ requirements. The honey chamber, properly so-called, ought to be more or less large, according to the local flora.
(1). I amplify the horizontal hive by giving it 20 frames, 38 x 38 cm. [nearly 15″ X 15″]; 11 frames for the brood, with a surface of 14.44 sq. dm., giving 158.84 sq. dm. of 700s, or 111,188 cells. This is the ideal hive for all, and especially for beginners – and they are not wanting (my goodness no!) even among the old hands!
All the frames abut on an entrance which can be as long as the hive; whence fresh air, more easy access to the storage space, rapid spreading of the nectar over a large surface and thus its rapid evaporation, easy inspection of any part, whether brood-nest or honey chamber. This hive is the one that seems to me to give least trouble.
(2). I amplify the vertical hive also thus: 12 frames, 30 X 45 cm. and 12 shallow frames 15 X 45 [11-1/2 and 5-3/4 X 17-5/8 nearly]. The 12 frames of the nest, each of 13.5 sq. dm., give 162 sq. dm. X 700, or 113.400 cells. For comparison, 12 Voirnot frames contain 111,708 cells and 12 Dadant frames, 115,668 cells, if 850 foundation is used.
The increase in size is justified, since otherwise the brood-nests are too soon crowded, whence danger of swarming. Big cells, big bees, a big hive.
To use 700 foundation, wire your frames vertically (7 wires for Dadant, 5 or 6 for Voirnot or Layens). Never any wires horizontal or crossed. It is better to put in one more vertical wire, to obviate buckling of the foundation. Having the frames ready, get them built: –
(1) By swarms. Feed if there is no flow, so that building may not be checked.
(2) By colonies that have swarmed, or by casts, whose young queens do not clamour for drone cells.
(3) By honey-storing colonies, outside the brood-nest, in the middle of the flow. The bees will not alter a single cell.
(4) Get the combs built, feeding heavily, at the end of July and in August. At this time the bees will not build drone cells.
Be careful not to introduce a frame with a sheet of foundation into the middle of the nest of a strong colony disposed to swarm; for such will alter some of the cells to make drone cells, even if you give them 900 cells per sq. dm.
I mention these matters specially, because it is those who make clumsy mistakes who serve as megaphones for the people who find it is not to their interest to encourage this innovation.
Do not let us, at the present day, be of the company of those beekeepers who ignore entirely the facts of contemporary practice, and who argue about things which they have never taken the trouble to try or to examine. It is enough to drive one mad. I hope that, fortified by all these little details, you will be able to prove to these people, by plain facts, what can be done by strong bees, reared in cells of 700 to the sq. dm.
For those who are not convinced, Tervueren is always there.