This month in the Hive
Wintering of Hives. – Further matters for action / observation
As winter develops, days become increasingly colder, more rain is received and significant changes are taking place within the hive. The collection of nectar and pollen are reduced, the queen slows down her rate of laying, drones have been mostly expelled from the hive and older bees from summer die off. In total, bee numbers decline from a summer peak of around 40-50,000 to around 10 -12,000 over winter
Over the last couple of month’s we have reflected on the need to consider the importance of:
- Choice of locality / site. (Drainage, increasing shade / diminishing sunlight.)
- Availability of appropriate stores of honey / pollen in the hive over the winter period.
- Adjustment of available space inside the hive to maximize warmth over winter.
Additional factors to consider:
- The Winter Cluster – When the temperature drops below 14 degrees, the bees congregate in the brood nest area, on and around the brood. They will crawl into some of the empty cells in this area and fill the spaces between the combs. The bees develop a formation similar to a “ball”. The outside layers of bees are packed tightly together, providing an insulation mat, with their heads facing the centre of the bee ball. Towards the centre of the massed ball of bees, where the queen is located, the concentration is not quite as dense, so these bees can move around to get food or care for any brood.
The temperature required to raise brood is about 35 degrees, so bees on the outside of the cluster vibrate their wing muscles to generate heat and warm the bees in the centre of the cluster. The bees on the top of the cluster do not have to work as hard as those on the bottom, as heat rises, warming those in the centre and at the top.
Bees on the outside cannot maintain their expenditure of energy for very long and move towards the centre of the cluster to increase their warmth and access the available food. Their role is exchanged with those that were previously more near the centre of the “ball” of bees.
As the temperature outside falls below 14 degrees, the cluster becomes even smaller as bees die off. The “ball” shrinks more in size, the bees move closer together, reducing the surface area of the ball and diminishing heat loss from the centre.
Keep in mind that bees do not heat all of the hive in winter, but only the area they form as the winter “ball” near the brood!! As practical as this may seem, there is a downside. If outside temperature becomes exceedingly cold and this impacts on the bees within a hive, the bees chill and may be unable to move to access their food supply even if it is within 5 cm or so. They can starve in the face of plenty!!! Hence the comment last month to not allow bees excessive room inside the hive in winter!
- Ventilation – Throughout winter the bees continue to eat honey, raise brood, form their winter cluster and move around the hive. These activities all generate heat, cause carbon dioxide and create water vapour from respiration. Whilst these activities also happen in summer, at that time the bees are ventilating the hive for the ripening of the nectar. However venting does not happen in winter as there is no nectar to ripen, thus these factors can be a significant cause for concern!
Without venting, the carbon dioxide accumulates, displacing fresh air, warm moist air builds up, and having no escape eventually comes into contact with the unheated sides and top of the hive. Here it condenses into water droplets, ultimately running down onto the bees or brood, chilling / killing them, or falls onto the floor of the hive causing dampness, and constant cold air to rise. Bees in such conditions quickly fall prey to disease and die.
This situation can be simply avoided by ensuring there is some form of ventilation available within the hive. If you have provided vent holes in the lid of the hive, check that the bees have not closed it up with propolis. They are less likely to do this if the vent hole cover is on the outside of the lid rather than the inside. If they have, remove the propolis.
Otherwise, lift the lid fractionally, by the use of a matchstick, (or similar) at the front of the hive only! That will allow the natural venting of the hive and avoid the aforementioned problems.
A further step taken by some beekeepers is to place additional insulation material (such as a polystyrene sheet or similar) between the hive mat and the hive lid, to reduce the impact of the coldness from rain and frosts thereby reducing condensation issues occurring from the lid area.
- Cleansing flights – Throughout winter there may be a period of time when it is unsuitable for the bees to exit the hive. This may be due to ongoing rain, severe cold, strong winds or a combination of several of these factors.
When a relatively warm, sunny day arrives you may observe a sudden emergence of a vast number of bees from the hive at once. Relax! They are not swarming!!! Rather, they are exhibiting on one of the key hygiene factors bees are noted for, not fouling their own hive. They are simply taking advantage of the “good weather” to take a cleansing flight. You may discover droppings, and dead bees, in front of the hive, as they “cleanse” themselves and the hive.
- Remember to regularly check the available “food supplies” within each hive by lifting it from the rear. If necessary take appropriate action to feed the hive.
- Keep alert to any possible water entering hive if it is located directly onto the ground.
- Be aware of the changing sunlight / shade / wind factors.
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