Chapter 5
V. Wintering So much has been written on wintering bees that it is not necessary to try the reader's patience by restating what has already been proven of the conditions that give best results. just in enumeration. Outdoor wintering. Strong in your bees. Sufficient honey of good quality. No disturbance. Entrance in hive in proportion to the number of bees. Hive. Sufficient insulation.
Sealed covers. Absorbent cushions. Inside wintering. Strong in young bees. Sufficient honey of good quality. No disturbance. Large entrance. Ventilation of good room. Temperature of room 57 degrees. Poor wintering is due to disturbance. Disturbances can be diagrammed as follows. Jarring, light, noise, poor honey, temperature of air surrounding the hive, humidity of air surrounding the hive.
The bee is so constructed that the temperature of its body can be reduced to 57 degrees. This reduction of body temperature the bee does not control, but it is the result of reduced temperature of the air surrounding the bee. The temperature of the body of the bee can be raised in two ways. First, by the temperature of the air surrounding it. Second, by a power inherent in the bee.
The bee cannot, of his own volution, lower his temperature below that of the surrounding air. Hence, to attain that condition of the body that gives winter's quiet and contentment, it depends wholly upon the temperature of the air surrounding it. This minimum body temperature has been found to be 57 degrees. When the temperature of air surrounding the bee is below this point,
energy is used by the bee to keep its temperature up to this safe minimum. The instinct of the bee leads it to do things not wholly for its own individual comfort, but for the good of the colony. For this reason, we find the bees clustered when the temperature of the hive air goes below 57 degrees.
The temperature of the cluster may be raised at the center to 90 degrees. The ones at the outside of the cluster are giving their bodies for isolation of the cluster. It is not known if a temperature down to freezing injures these exposed bees. Bees have been revived after exposure for some time to a very low temperature. If the reader will keep in mind this relation of temperature to the bees,
the effect of humidity of the air on a colony of bees will be better understood. It is evident to every person wintering bees that humidity plays an important part in success or failure. Temperature and humidity are so related to each other that temperature controls the absolute humidity of the air at saturation, as the following tabulation shows.
Temperature versus vapor weight per cubic foot at saturation measured in grains. 0 degrees, 0.54 grains. 10 degrees, 0.84 grains. 20 degrees, 1.3 grains. 30 degrees, 1.97 grains.
40 degrees, 2.86 grains. 50 degrees, 4.09 grains. 60 degrees, 5.74 grains. 60 degrees, 5.75 grains. 70 degrees, 7.99 grains. 80 degrees, 10.95 grains. 90 degrees, 14.81 grains. 100 degrees, 19.79 grains. Where we find a colony with diarrhea, we find even the frames and combs damp. This is the condition of most colonies that are dead or very weak in spring.
Honey has an absorbing power for water, and in a moisture-laden air will absorb great quantities of it. When honey gets thin and watery, it is not good feed for bees, and with such a diet the system soon clogs, and we're all familiar with the results. We naturally ask the cause of this moisture-laden air. Most beekeepers give respiration of the bees as the cause. One day in the fall I took a seal-tight cover from the hive and held it
so that the drops of water that were condensed on its inside surface could run down to a corner of the cover. Then I poured out a little more than two ounces of water. What yet remained on the cover I estimated to be one ounce. Three ounces of water condensed on the cover.
No estimate was made of the amount on the hive walls. Did the bees breathe out that much water the previous night? One of the axioms of physics is that something cannot be produced from nothing. If bees are confined in winter quarters 120 days, and they consume 30 pounds of honey, of which one-fifth is water,
making the consumption of 6 pounds of water during the winter, or 1 and a quarter of an ounce for one day, could they breathe out all the water that they eat? This amount falls way short of the amount that condenses on a seal-tight cover in a single wall hive on a cool night. Outdoor Wintering. The ordinary beekeeper cannot keep his
bees at a uniform temperature, neither can he control the humidity of the air. So his bees have a fluctuating temperature to overcome, and consequently, a changing humidity. This changing humidity is the one great unseen cause of disturbance in bees. A clear understanding of the laws of meteorology that relate to moisture in the air will be necessary to comprehend where this water vapor comes from. The amount of water vapor in the atmosphere is ascertained by using
two tested thermometers. One, called the dry bulb, is exposed in the temperature noted. The other one has a cloth covering the bulb. This cloth is moistened and the thermometer whirled in the air for a short time and the temperature noted. Then, by subtracting the temperature of the wet bulb from that of the dry bulb, we have a basis for computing the dew point, and from this the relative humidity. Knowing the temperature of the dew point and the amount
of water vapor that saturates the air at that temperature, we have the absolute humidity. Divide the absolute humidity of the dew point by the absolute humidity of the dry bulb temperature and you have the relative humidity. Air can be supersaturated. That is, it can contain water in excess of that which saturates it at its temperature, but this excess water is held in the air in globules of water and is known as fog or clouds. The excess water has given up all of its gaseous
properties and is not subject to the same laws as the water vapor of the air. The gaseous vapor of the air is controlled by the same laws in regard to its expansion and contraction as air. It is well known that if a chamber in which the air is rarefied is opened, the air rushes in from the outside until the outside and inside air have the same density. Water vapor does not rush into a hive, where the hive air is relatively dry and a small opening is maintained, but is
slowly forced in until its tension at hive temperature equals the tension of the outside vapor at outside temperature. Because of this slow movement of water vapor, when its tension inside the hive is greater than on the outside, it condenses on the inner walls, or is transformed into fog, which then looses the expansive power of gas and is retained in the hive.
Disturbance inside the hive which causes the bees to raise the temperature of the hive air, with its then greater capacity for moisture, or a fall of temperature, or raise of relative humidity outside, give an unequal vapor tension and cause vapor to pass from the outside into the hive. When the hive air is cooling, it loses some of its moisture which is condensed in the hive. To illustrate, assume a hive temperature of 57 degrees and an absolute humidity of 4 grains,
which temperature is raised to 70 degrees and still 4 grains of moisture. To equalize the tension of the vapor inside and outside, some moisture is slowly forced through the opening. Let us say until this 70 degree air holds 6 grains. When this air is reduced to 57 degrees and an absolute humidity of 4 grains,
2 grains of water is left in the hive after this disturbance. Suppose the hive is not insulated. No thickness of insulation is too much in any locality whose temperature falls below 50 degrees. And the outside temperature drops to 32 degrees. The hive temperature drops from 57 degrees, humidity 4 grains, to 40 degrees.
At 40 degrees, air is saturated with 2.86 grains. In this case, about 1.5 grains of water is left in the hive. Let us pass the next cause, the change of humidity of the outside air. Assume a maximum temperature of 40 degrees, a relative humidity of 84 degrees, and an absolute humidity of about 2.30 grains. The hive air at 50 degrees, a relative humidity of 74%, and an absolute humidity of 3 grains.
To equalize the tension of the vapor inside and outside the hive, a constant movement of vapor into the hive is taking place, which, when it is equal to the humidity that the condensing surface of the hive can maintain, is being constantly condensed on the inner surface of the hive. Consider the amount of vapor that is constantly passing into the hive on days when the relative humidity is 96%.
There are many days in the more southerly states where a 100% relative humidity obtains. Because of the small amount of moisture with which a zero atmosphere is saturated, 0.54 grains, bees in the north have less moisture to contend with than in the south,
where the temperature ranges from 32 degrees up to 60 and 70 degrees. In the latter locality, absolute humidity of 32 degree air at saturation is 2 grains. At 60 degrees, it is 5.76 grains. In the colder localities, with a temperature of 0 or lower for weeks at a time, insulation is necessary to protect the bees from the cold,
and in the spring and fall to protect them from excess moisture. In localities where the cold is not so severe, but that the bees can beat back what little cold comes in at the entrance, insulation is necessary to keep the hive dry. In the north, we insulate to keep the hive warm and dry.
In the south, you should insulate to keep the hive dry. The question naturally arises as to how insulation keeps the hive dry. How it keeps the hive warm is obvious, because atmospheric vapor and temperature are so correlated that they must be considered together. Heat is communicated in three ways.
By conduction, when it travels from particular to particular, in the substance heated. By conviction, when the particulars of the substance heated moved away from the source of heat. By radiation, when the heat travels through space in all directions from the heated substance. Insulation has to do with heat communicated by conduction. A substance that is a poorer conductor is a good insulator.
The escape of heat from a substance or space depends on the amount and quality of insulation surrounding the substance or space. The fireless cooker is a good example of what insulation does. The wood of which a hive is made is the insulation that surrounds the hive air. Add to this insulation a uniform thickness of leaves, sawdust, chaff, or any other insulator, and you make it harder for the heat to pass out of the hive by conduction.
Hence, a well-insulated hive has a temperature more nearly uniform than a single-wall one. The temperature of a hive could easily be kept uniform if the bees did not have to have air. An air opening must be left for ventilation. Because of this, heat is passing out of the hive by convection. Not much heat passes through this opening by radiation or conduction,
as air absorbs heat slowly and does not readily part with it. The escape of heat where the opening is not too large is not great and the radiation and convection of the heat from the bees will balance that, where the outside temperature is not very low. Where they have both opening and single-walled hives, poor insulation, to contend with, they exert energy and the consequent consumption of stores to supply the loss. The more insulation, the greater the number of bees in the hive, the more the temperature of the hive air lags behind as the outside air changes. The hive vapor under these conditions moves out slowly and does not saturate the hive air.
When a colony of bees cluster, they create for themselves a hive within a hive. The insulation of the cluster hive is the bodies of the bees on the outside of the cluster, and the colder the hive air, the better they make this insulation. Let us now indulge in a little speculation. It is an established fact that the heat of the inside of the cluster increases
as the hive temperature falls and vice versa. The honey stores are mostly outside of the cluster and exposed to the vapor of the hive. We know that the bees have ways of controlling the vapor of the hive in summer. May it not be possible that the rise in the temperature of the cluster is for the purpose of increasing the lag in temperature.
This may mean a great deal to them by protecting their honey from moisture. Absorbent Cushions As understood by beekeepers, any porous material placed between the cover and frames for insulation is an absorbent cushion. Claim is made that moisture escapes through this cushion. Sometimes the moisture has tried to escape this way, and in the spring, the cushion is wet.
Sometimes the cushion does not fit snug against the super, and an opening is left which gives upward ventilation. Moisture here travels in the path of least resistance, and poses off through the largest opening it can find. If a close examination is made in the winter, frost will be found where the moisture is passing out and the cushion found dry. Sometimes the cushions are found dry where the burlap is laid across the top of the hive and the super set on this and filled with packing. If his burlap is examined, a great deal of propolis is found on it, put there by the bees to prevent upward ventilation.
Sometimes his cushion is found dry because the inside of the hive is well varnished with propolis. the insulation is good, which conditions keep the hive air at the proper humidity. The temperature of an insulated wall, which has an unequal temperature on its opposite side, will, at the points with this wall, be influenced by the distance that these points are from the surface. If the outside temperature is 10 below zero, the first quarter of an inch on the outside
part of this insulation will be about 10 below zero. The inside surface would be about hive temperature. Unless the laws of nature are bent or broken, water vapor would not travel far in this material under these conditions without being condensed. In winter as well as summer, the big part that a well-varnished hive and the consequent condensation play can be seen. Most beekeepers winter their bees in hives used a year or more. These hives get good results in
proportion to the way that they are varnished with propolis and sealed at the top. When all hives are well varnished inside, a seal-tight cover provided, and other necessary things pertaining to good wintering, such as bees, food, sheltered location, insulation, and a clear entrance, bee conservation will have advanced. Indoor wintering Indoor wintering differs from outdoor wintering in that the repository where the hives are stored is the regulator of the temperature and moisture instead of each individual hive. A good cellar or other repository where a nearly uniform temperature of 50 to 57 degrees is maintained and well ventilated is an ideal place to winter bees.
When setting the hives in the cellar, remove the bottom board from each hive, then forget that the bees are in individual hives, and think of your cellar as one big complex hive. About the only use there is for a hive in the cellar is that it is a convenient place to hang the frames. If the temperature and ventilation are good, and the cellar dark, the bees will winter, as well as if the frames are taken out of the hive and hung on a rack and properly spaced. Small entrances are the primary cause of more dead bees than anything else.
Condensation takes place in a hive with a small entrance for the same reason as given an outdoor wintering, a change of hive temperature caused by some disturbance. The bottom board must be left off to eliminate this moisture trouble. This gives an equal temperature to hive walls and hive air, and makes condensation on the hive walls impossible.
If a colony of bees give off much moisture in respiration, and there is no doubt that they give off some, it is easily diffused through the air by means of the large opening at the bottom. Let us remember that what we are trying to prevent is excess of moisture in hive air, and that we control it by our control of the temperature of the repository.
Temperature and its relation to moisture is the keystone to successful wintering. Conclusion When we compare evaporation by the aid of ventilation with that which takes place aided by condensation, and give this an application of the laws of heat, with its three ways of communication, conduction, convection, and radiation, the tension of vapors,
and the stillness, dryness, and density of the atmosphere, our conclusion must be that condensation is so uniform in its results that it eliminates everything ascribed to locality but the number of flowers and the weather conditions that affect the flight of bees and the flow of nectar. All other conditions, by the aid of condensation, can be controlled by the beekeeper. Ventilation and shade each make more room in the hive, but not with uniformity under all conditions.
So we must add to the treatments we give the bees. a well-varnished inner surface to the hive, and a cover that at no time permits upward ventilation. Then the bees will be able to keep the nectar out of the way of the queen, whose egg-laying capacity is increasing daily. Room and the procedure whereby the bees automatically make more room as they need it
is the single thing that we have to consider in urge prevention. End of Section 5 End of Constructive Beekeeping by Ed Clark
