wrapping up the hive for winter
Bees work hard all summer and fall to build up their honey stores and have enough to stay warm and well fed all winter. While the types of bees that are generally raised in Canada are originally from temperate climates, they have adapted to the cold Canadian winters by clustering in a ball and eating their own stored honey to stay warm.
Honeybees don’t hibernate, they are active all winter, but stay in the hive in their cluster and vibrate their wings to generate heat. The worker bees have kicked out all of the drones as superfluous to the health of the hive and hunker down to wait for spring. As mentioned in an earlier post, bees won’t go to the bathroom inside the hive, so they’ll wait for the end of winter or a warm day when they can dash outside to relieve themselves.
There’s two main issues that can cause a hive problems in the winter: starvation and moisture.
Yes, the obvious reason a bee hive can starve over winter is if not enough honey is left for them by their beekeeper, or they weren’t able to amass enough stores to see them through the winter. In addition to that, though, bees can still starve over winter with more than enough honey in the hive because of accessibility issues.
There are a few reasons why bees may not be able to access all of the honey they have in their hive. Clustered bees tend to move through a hive in one direction only. For top-bar hives, this means that the ball of bees could start in the middle of the hive and, over the winter months, move towards the back of the hive, eating honey as they go. If they get to the end of the hive, they won’t turn around and find the honey at the front of the hive — they’ll think that they’ve run completely out. Another possibility, related to the moisture-control problem that we’ll talk about below, is if water freezes into an ice chunk between combs and cuts the bees off from their honey stores.
The average honey bee hive will need anywhere from 60 – 100 lbs (30 – 45 kg) of honey to get through a Calgary winter (that can last from October to May) and a lot of commercial beekeepers will feed their bees with additional syrup resources to ensure that the bees have enough food — especially if the beekeeper has taken a large portion of honey out of the hive.
For us, we would rather not get in the habit of feeding our bees a low quality sugar solution nor have the bees be dependent on our feeding to get them through a winter. We may provide some of their own honey back to them in the spring if we think that they are low and flowers haven’t arrived yet, but outside of that we haven’t made plans to feed. We hope that our bees have enough honey to get them through the winter. We harvested about 5 L this year with the last harvest being in the 3rd week of August. Hopefully they were able to restock and will have enough!
“The honey consumed by bees is broken down into carbon dioxide and water. For every gallon of honey consumed, and almost equal volume of moisture is given off in the hive. Unless adequate provision is made for the escape of this moisture, colony mortality may be high. When clustered, bees are unable to ventilate their hives by fanning. Therefore moisture must be removed by convection currents, or it will condense in the hive” (Root, A. ABC and XYZ of Bee Culture, 1978).
If you have condensation in the hive, you are going to have ice. Ice can block the bees from their honey and will also suck heat out of the stored honey kept warm by the bees. You can also end up with mould problems which can cause health issues for the bees.
Surprisingly, the winter cold is not one of the main reasons a hive may not survive the season. Since bees are cold-blooded, their metabolisms and activities adjust to withstand the cold. The ABC and XYZ of Bee Culture (1978) has a great analogy about bees in the cold:
“Why Packing for Outdoor-Wintered Colonies?
It is only natural and logical to believe that double walls to a house would save fuel over a building where the walls are of only one thickness. Why would not the same principle apply to a bee hive? The cluster of bees within would be a source of heat like a furnace pr a stove in a house. The colder the outside atmosphere the more honey (fuel) the bees would consume. The colder the outside the more fuel (coal) the furnace or stove would burn in a house. This argument on its face is more convincing than true.
Bees are Cold-Blooded Animals
Up to this point the parallelism ends. Beyond this there is a big difference. In a house the occupants are human beings and therefore are warm-blooded and so can not stand a reduction of body temperature which must be kept at near 98 degrees F. To do this man must wear clothes and in addition have a room temperature of 70 or 72 degrees F maintained by the consumption of coal, oil, or gas. The occupants of a bee hive are bees and, as a science tells us, are cold-blooded animals. The body temperature of bees can drop from 94 degrees F [34°C] summer brood rearing to around 43 degrees F on the surface of the cluster. When the outer shell temperature goes as low as 27 degrees F [-3°C] bees die. Bees in the outer shell one or more inches deep can stand 43 degrees F [6°C] for a long time provided they are kept supplied with food by the bees from within.
Bees raise the temperature in the cluster when it turns colder outside in two ways: (1) by contracting the cluster so as to reduce the outside surface and (2) by activity when the surrounding temperature drops below 57 degrees F… It will be noted that there is a considerable range of temperature of the winter cluster because bees are cold-blooded animals can adapt themselves to such variations while we humans can’t stand a continuous body temperature of much below 98 degrees F.”
We did prepare our hive a little bit to help address some of the heat and moisture issues. We insulated the sides of the hive and the top of the roof with styrofoam R12 insulation. Between the last honey comb and the back of the hive, we slid the false back up to pack it in as close as possible. The leftover space between the false back and the actual back of the hive was filled with R20 fibreglass insulation. We put a thin layer of fibreglass insulation on top of the top-bars and put the roof over top of that.
On the outside of the hive, we wrapped everything but the front face with Tyvek® so that moisture could escape outwards, but not move inwards. The wrap will also help keep wind down and stop convective heat loss from the hive. Finally, we drilled a few holes into the front face of the hive to help allow moisture to escape and provide another exit for the bees.
This was our best effort in preparing our hive for winter. The Calgary beekeeping group Apiaries, Bees & Communities has a great (free & downloadable) resource that describes techniques for winterizing hives. We’ll be keeping our fingers crossed that our bees survive their first winter, but we’re also trying to stay grounded and acknowledge that a lot of hives don’t make it.
Fun fact: Brandon Manitoba had a historical experimental farm that was set up in 1886 and studied winterization techniques for keeping bees from around the 1930s onwards! If bees can survive a Canadian winter in a place like Brandon, hopefully we can figure out how to keep bees alive in urban Calgary!
Leave us a comment! Any other suggestions? Do you think we need to shield against mice?