Getting Bees Safely Through Winter
To survive winter a colony of honeybees needs to be strong and in good health. The colony needs a safe nest, enough food and protection from predators. There are many ways a beekeeper can help prepare bees for winter throughout the previous season and a few things that should be avoided as they would hinder the colony.
A Strong Colony
A colony needs a sufficient number of bees to cluster tightly together for warmth overwinter. Colonies left to swarm and cast the previous summer may be too small to survive. Small colonies, provided they are healthy, might be better united together, although it is possible to overwinter a well prepared five or six frame nucleus, especially in a well insulated polystyrene nucleus hive.
Summer bees may only live six weeks, but winter bees need to survive six months, so it is preferable to start winter with plenty of young bees. A younger queen will tend to lay later into the autumn producing these young bees. An older queen could run out of sperm over winter and lay only unfertilised drone brood in spring leading to the demise of the colony. Colonies sensing their queen is old may replace her late in the season by supersedure. A beekeeper finding just a couple of queen cells late in the season, often on the face of the comb, might be wise to leave well alone and allow the colony to raise themselves a new queen.
As discussed above, a populous colony is best for winter. Colonies can be weakened by both brood diseases and adult bee diseases.
Brood diseases will reduce the number of live bees emerging; foulbrood must be dealt with by the National Bee Unit. Colonies with bad chalkbrood or sacbrood virus are best requeened in the summer.
Adult bee diseases such as Chronic Bee Paralysis Virus or Nosema will shorten the lifespan of individual bees, meaning the colony population may be too low to survive until spring. Nosema is reduced by clean combing and prevented from spreading by practicing good apiary hygiene throughout the season.
Varroa population and associated viruses are likely to be highest at the end of the summer.
Most beekeepers apply an effective Varroa treatment after honey harvest, so the mite population is as low as possible going into winter. Some treatments which take several weeks need to be applied in August, to allow time to complete feeding afterwards. Oxalic acid Varroa treatments should be used in broodless conditions; around Christmas time.
A Safe Place
Bees need a dry cavity to overwinter in; damp can kill a colony. In autumn bees will propolise hive parts together to make their home watertight. As the weather gets colder, bees cluster together and cannot reduce humidity by fanning as they do in summer. The cluster itself will produce some water vapour from respiration, so a little ventilation is necessary. Open mesh floors provide plenty of ventilation so holes in cover boards can be closed. An empty super or similar under an open mesh floor, like a kind of skirt, will reduce drafts. With a solid floor or blocked mesh floor, providing a little top ventilation will allow air to circulate.
Some beekeepers insulate hives for winter, either with a layer of insulating material over the cover board or right over the hive like a tea cosy.
The hive entrance must be kept clear in winter both for ventilation and to allow bees to go on cleansing flights or short foraging trips. Ensure entrances are above possible snow levels. Putting the entrance block upside down may prevent the entrance becoming blocked by a carpet of dead bees falling from the cluster to the floor. Positioning hives such that winter sun shines on the entrance should encourage cleansing flights and reduce disease.
Use strong hive stands. If the hive stand has four legs, place it on a slab or bricks so the legs don’t sink in waterlogged ground causing the hive to fall over.
Apiary sites should be sheltered from prevailing south-westerly winds and any cold winds either from the north or east. Roofs can be secured with bricks. Check hives following gales. If a hive blows over, stand it up and gently reassemble it, often all is well come spring.
The reason honeybees forage in the summer is to store sufficient food for the colony to survive winter when less plants are in flower and the weather is not conducive to flying. A strong colony needs 40lb of ripe sealed stores to survive winter.
Once honey supers have been removed, the weight of stores can be assessed: An estimate can be made either during an inspection (each full British Standard brood comb weighs approximately 4lb), by hefting the hive, or by weighing the hive with luggage scales and subtracting the weight of the empty hive. If necessary, the colony should then be fed. Food could be combs of honey, unsaleable honey or sugar syrup. Stores entirely of oilseed rape or ivy honey will crystallize and be more difficult for bees to eat than liquid food. If leaving a super of honey on the hive, remember the cluster will form below stores and gradually move up as they consume food, therefore it is important to remove any queen excluder from between boxes so that the queen is not left behind! A bucket of fermented or unpalatable honey (provided the source is known to be disease free) can be heated to 60C to kill yeasts, diluted 1:1 with water and used as autumn feed. Sugar syrup should be made with white granulated sugar and water (other sugars can give bees dysentery). Autumn feed should be as concentrated as possible because bees need to concentrate it further to preserve it for winter. A thick syrup is 2 lb sugar to 1 pint of water. Use hot water and stir, but don’t boil as excess heating of sugar produces toxic breakdown products. Allow syrup to cool before feeding to bees. Ready made syrup is commercially available.
Many types of feeder exist. Using a feeder which bees cannot drown or defecate in will help prevent disease spreading. It is important to put food on the hive at dusk. If a bee finds a food source in the middle of the day, she will dance the round dance alerting all her sisters to a new food source within 100 yards, causing them to rush from the hive and search. This may upset people nearby and start bees robbing other hives. By adding feed at dusk, the bees find the new food source overnight and all is calm. Additional precautions against robbing are keeping entrances small, avoiding spilling syrup and feeding all colonies in the apiary at the same time. Once started, feeding needs to be constant and plentiful so that bees store food. A stop start trickle of food will merely stimulate the queen to lay instead. It is advisable to complete feeding by the end of September. After this the weather may be too cool and damp for bees to ripen and store liquid food. It may give them dysentery and spread disease.
Adult bees eat much pollen in autumn and store this in their fat bodies as food reserves. The bees also pack pollen, preserved with a little honey, into cells and cap this as protein reserves for winter and early spring when there is new brood to feed. Pollen supplements or pollen substitutes are used by some beekeepers wishing to build up colonies for an early spring honey flow.
Choosing an apiary site with plenty of autumn forage nearby and not keeping too many colonies in one place will help bees collect and store the pollen they need for winter. Once the colony has the required food for winter, ripened and stored away, they should survive until spring.
The weight of hives can be monitored throughout winter. In cold conditions when the queen is not laying, stores will be used slowly. Once the queen starts laying in the new year, stores will be used more quickly. Roughly one comb of food is used to raise one comb of brood. If it is judged that extra food is required in the cold winter months, fondant should be placed directly above the cluster.
The month of March can be critical; the colony has increasing amounts of brood to feed, last year’s adult bees are reaching the end of their lives and food reserves are low. This is a time for extra vigilance, especially as the weather can swing from winter to spring and back again.
Protection From Predators
In late summer wasps can start trying to rob beehives and can destroy whole colonies in a bad year. Reducing the hive entrance helps bees defend themselves. An entrance can be reduced to one bee space if the colony is troubled by robbers. Beekeepers make wasp traps with all kinds of bait; water with jam or beer for example, bees are not attracted to these but don’t use honey as bait! Adding a drop of detergent breaks the surface tension and drowns wasps more effectively. Keep refilling traps for as long as necessary. If wasps are very troublesome it is worth searching for wasps’ nests and destroying these at dusk with commercially available pesticides. Bees can also rob other bees; small, weak or nucleus colonies are especially at risk. Once bees are clustered, they will no longer have guard bees posted at the entrance, so are vulnerable to other predators such as mice and green woodpeckers. Mice looking for a dry place to spend winter and a food supply will enter hives in autumn disturbing clustered bees and eating their stores. Mice can be denied access by a 3/8 inch circle such as the holes in a mouse guard or a 5/16 inch slot such as a new, unworn entrance block.
Green woodpeckers usually eat ants, but when the ground is frozen hard they peck holes in beehives to find food. They disturb the cluster, eat bees and brood, expose the colony to the elements and cause much damage to hives. A loose wrapping of 25mm wire netting around the hive during December, January and February will prevent woodpeckers getting a foothold on hives, but bees manage to fly through the wires.
Having prepared colonies well beforehand, beekeepers should not open hives unnecessarily over winter as this will stress the bees causing them to break cluster and use up precious stores. Rather they should regularly heft hives, check apiaries for damage after storms and visit on warm, sunny days to see the reassuring sight of bees flying and taking on a little pollen. If curious, a monitoring tray can be placed below a mesh floor for a couple of weeks in winter. The debris will show the size and position of the cluster and other clues as to what is going on, without disturbing the colony.
Owner: Executive Committee