The incidence of colony mortality is far greater in the winter than at any other time. This is generally due to the bees being confined to their hive for long periods, and any problem, such as disease, queen failure or depletion of stores, cannot easily be rectified. The beekeeper is unable to detect any winter problems within the hive, for the weather is usually too bad to risk opening up and disturbing the winter cluster. Careful preparation for winter therefore, is vital to both bees and beekeeper. The three potential problems already mentioned are worthy of closer scrutiny, as preparations are made in September.
If the colony has been disease free through the summer, then there should be little to worry about as they go into winter. There are however, some precautions worth taking. Nosema, which is endemic in many areas, can be combated at this time of year, simply by adding Fumidil B. to the winter feed. Dysentery is a winter killer, but it can be avoided. It is usually brought about by fermenting stores, or honey with a high fibre content. Fermenting stores are usually caused by the beekeeper feeding the colony too late in the season, allowing the bees too little time to store the honey, reduce the moisture content, and seal the cells, before being forced by temperature into the winter cluster. Feeding should be finished by the end of September to ensure sealed stores for the winter.
Strange though it may seem, the bees' own honey is not always the best food to see them through the winter. Some honeys, such as heather and honeydew, are high in fibre, and if this is the only food available, it results in the bees need to defecate more frequently. If the winter weather prevents cleansing flights, then dysentery occurs on the combs, and will spread quickly through the colony. It is therefore beneficial for the bees to be fed at least some sugar syrup, in order to ensure that their winter stores will not harm them.
This usually occurs in an ageing queen, so the remedy is simple. Make sure that the over-wintering colony is headed by a queen not more than three years old, preferably two.
Depletion of Stores
Starvation is one of the principal reasons for bees failing to make it through the winter. They are unlikely to succumb in the depths of winter, when the colony is tightly clustered and little stores are being used, but in March, when the brood nest is rapidly expanding, with the resulting strain on already depleting stores; starvation is a real possibility. Although the weather at this time of year may still not be conducive to opening the hive, the weight of stores can be roughly checked by “hefting” the hive, and if necessary, the feeder must again be brought into use. Feeding is best done in September however, and if sufficient is fed at this time, then starvation should not be a problem. How much is sufficient? This is a question which is often debated by beekeepers, who hold differing views on the amount of stores necessary to see a colony through the winter. To approach the problem scientifically, the amount of stores already in the hive should be determined, and then supplemented with the correct amount of sugar syrup. A sensible rule of thumb however, is that if the bees are fed 3 gallons of heavy syrup (2lbs sugar to 1pt water), they will run no risk of starvation, and if any is left in the brood chamber the following spring, then the new incoming spring nectar can be taken straight up into the supers.
Pests, Predators and Parasites
This is another area where the beekeeper’s winter preparations are vital to the bees. The honeybees’ principal parasite is the Varroa mite, and without man’s intervention, they would succumb to this infestation. Complete eradication of the mite is unfortunately, not an option, so several management techniques have been developed to reduce the over all number in the hive. These include Queen Trapping, Drone Culling, the use of Icing Sugar or Talcum Powder, Open Mesh Floors, and Alternating Treatments. By integrating some of these management techniques, Varroa control is not difficult. Details of all these techniques can be obtained from the National Bee Unit, but let us concentrate here on the simple basic operations, which take the minimum of time, and have the desired effect.
It is claimed that twenty to twenty five per cent of Varroa mites, at some stage, lose their foothold and drop to the floor. If a solid floor is being used, the mite simply hitches a lift on the next passing bee, and before you know it, it is back up among the cluster. If however, an Open Mesh Floor is used, these mites will drop through onto the ground below, and that’s twenty to twenty five per cent of the problem solved, and it takes the beekeeper no time at all. This type of control can be used both winter and summer. All Open Mesh Floors should include a tray, which can be slid in below the mesh, and which can be used to monitor natural mite drop. The tray is usually installed for a period of five days, after which the number of mites can be counted, and used to calculate the level of infestation within the hive. Another simple method of checking Varroa levels is to extract drone pupae from their cells using an uncapping fork. If the prongs of the fork are inserted just below the surface of the cells, a number of pupae can easily be removed for inspection. The reddish mites will show up very clearly against the white pupae.
Drone Culling is another method of removing a number of mites, and this can be done in conjunction with open mesh floors, and takes very little time. It is a recognised fact that Varroa mites prefer to reproduce in drone cells, because of the extended period in which the drone pupae develop. Therefore, if drone brood can be encouraged for a short period, the mites will be encouraged to migrate into these drone cells, and when capped, the brood can be sacrificed along with a substantial number of Varroa mites. This can best be achieved in the spring, when the bees are anxious to produce drones for the coming season. By placing two shallow frames of worker comb in the brood chamber, the bees will be induced to draw wild comb below the bottom bars, to fill up the excess space. In spring, this comb will most likely be drone comb, and will attract Varroa mites. When the cells are capped, the frames can be removed, and the wild drone comb cut off and destroyed. The frames, which now contain only worker brood, can then be returned to the brood chamber, where the operation can be repeated until the wild comb is eventually drawn down as worker comb. At this point, the frames should be worked, in stages, first to the edge of the brood nest, where the worker brood is allowed to emerge, and then to the outer edge of the brood chamber, where they can be replaced with normal brood frames. Two points worthy of mention here are that the two shallow frames should not be placed in consecutive positions, as the space created below could result in uncontrolled wild comb being produced. The frames should be placed in the centre of the brood nest, either side of a normal brood frame. Secondly, care must be taken not to allow the resulting drone brood to emerge, for if that were to happen, we would be breeding mites, not controlling them.
As we approach the end of the summer, the bees, in preparation for the coming winter, are reducing the brood area. Because the number of cells in which the mites can hide is now greatly diminished, it is a good time to consider treatment. Initially, when Varroa was first discovered in the UK, the only treatment licensed was Bayvarol, a pyrethroid based treatment. After a few years, this was joined by Apistan, but this was a similar product with a similar base. Within ten years, Varroa had developed a resistance to pyrethroid. An alternative treatment was required. For several years, Vita (Europe) Ltd had been developing a thymol-based product called Apiguard. This was granted a licence and became a legitimate alternative. Sensible husbandry now consists of alternating treatments on an annual or bi-annual basis.
Both types of treatment are easily applied, although there are differences. Apiguard is a thymol-based gel, which functions in two ways. The slow release gel evaporates, producing a vapour, which is heavier than air, therefore open mesh floors should have their trays in place, or the hive placed on a solid floor for the period of the treatment. The second way in which the treatment works is by the bees physically removing the gel, and carrying it down between the frames effecting further dispersal. Of course, in order to do this, they must have access to the trays in which the gel is applied. The trays are placed immediately on the top bars of the brood chamber, immediately following removal of the honey crop. First one is put in place, then two weeks later another joins it, and the two are left in position for a further four weeks, making a six week treatment in all. In order for the bees to have physical access however, the trays require housing, for if the crownboard is placed immediately back on the brood chamber, it will effectively seal off the tops of the trays. This housing is usually effected by the use of a two inch eke, and then the crownboard placed on that. Because thymol relies upon evaporation, the treatment is temperature sensitive, requiring a minimum of 15c; therefore treatment must begin in August, as soon as the honey crop has been removed. If it waits until September, the ambient temperature towards the end of the treatment period might render it less effective.
If a pyrethroid based product (Bayvarol or Apistan) is being used, this is even easier to apply. These are contact treatments, relying upon the bees crawling over them. Both brands take the form of impregnated strips, which are hung down between the brood frames, and left for a period of six weeks. Because the treatment does not rely on evaporation, it can be applied in September, bearing in mind that the later it is applied, the further into winter it will be when removal is necessary.
Included among the pests and predators that can be a problem in the winter, are mice, woodpeckers and badgers. Of these, mice are probably the most prevalent. During the active season, a mouse wouldn’t dare set foot inside the hive entrance, but in the winter, when the bees are tightly clustered; it is very easy for one to creep in without detection. A beehive is ideal winter quarters. It is warm, dry, and has a built in food supply. Once inside, the mice usually make a nest, which means the destruction of combs and frames. The remedy is simple however. A mouse guard placed across the entrance, and secured with drawing pins or clips, will keep the mice at bay.
Woodpeckers are usually only a problem in a very hard winter. If the ground becomes frozen for long periods, they will sometimes attack beehives, drilling their way through the side of the brood chamber, and completely ruining it. The answer to this problem, when it occurs, is chicken wire wrapped around the hive.
Badgers, again, are not usually a problem. They will sometimes scratch at the hive entrance, dislodging the mouse guard, and they will sometimes put their front paws on top of the hive in an effort to push it over, but if the hive is on a firm support, they will not succeed. A good heavy stone on the roof will help to keep it stable.
Finally, there is the weather to consider. Cold doesn’t kill bees, damp does. Ventilation is even more important in the winter than it is in the summer. Any entrance blocks should be removed before fitting mouse guards, and the entire entrance left open. This, together with open mesh floors will ensure adequate ventilation from the bottom of the hive. The feed holes in the crown board should be left open, and the ventilation outlets in the roof should be freed of any blockage. It is worth mentioning here, that the crown board should be a ply wood type, not glass, as glass will collect condensation, which will drip down onto the bees and could be fatal. In some exposed areas, the winter gales can sometimes blow snow or rain in through the entrance, so unless an open mesh floor is being used, a batten should be placed under the back of the hive, tipping it forward slightly, so that any water that finds it’s way in, can run out again.