Preparing & Wrapping bees for a cold Minnesota winter

Winter comes quickly in North America, and it lasts a long time. This year, our winter started in mid October. Temperatures fell below 30F and snow was flying. That means, we prepped the bees earlier than usual. Read below to see our winter hive configuration and all the steps we take to make it through a long 6 month winter.

Because our weather is variable, we follow plant cues more than dates. For example, we stop taking out frames for inspections by the time the leaves have started to fall off the trees. They have long since changed color, but when they start to fall, the trees are telling us winter is just moments away.

We check the weather forecasts too. Nights dipping into the 40F range mean we are cooling down rapidly and we need to finish up our fall preparations.

A few things to keep in mind when you are preparing for winter.

  • We want to maintain a propolis seal in all the of the boxes. This keeps out wind and helps the bees maintain their heat.
  • We want to be sure we treated for mites throughout the season.
  • In Minnesota, we want our bees to have built up 3 deep 10-frame boxes so they have adequate food for a 6 month winter.
  • Mouse guards go on as soon as the leaves change color.

We went into 2020 with all of this in check. We stopped pulling apart the boxes and frames in early August. That is also when we did our last Oxalic acid dribble to treat for mites. This gave the bees 1 1/2 months to reseal their home. We monitored the bees for food levels as we headed into the fall. They started to dip into their reserves during the August drought, so we did some supplemental feeding.

We had a severe drought this summer, so we used robber screens for all of August and September.

In September, when the leaves start to change color, we put on our mouse guards. These are an easy and inexpensive DIY project. Just buy 1/4″ mesh from the hardware store and cut them to fit. You can use staples or push pins to secure them to the hive.

We put our entrance reducer in front of the mouse guard to slow the wind. Yes, this makes it difficult for our bees to clear out their dead and effectively blocks this entrance over the season.

Keep in mind that this entrance will also soon be buried in snow, and our bees will not be able to fly out for any reason until February or March, so blocking this entrance is not the same concern as it may be in warmer climates. Air can still get in/out. Bees can not.

We will remove the entrance reducer around the middle of February – which is when our solar radiation levels are strong enough for plants to take notice. (Fun fact, our house plants rarely grow at all throughout the winter but perk up and begin growing slowly in mid-February.)

By October, our trees started dropping leaves and our weather started ranging between 20-55F. This when we decided to pull our feeders and wrap our hives.

Wondering what type of feeder we use? We use a very inexpensive DIY feeder that results in almost ZERO bee deaths – check it out here.

You can wrap your bees in almost anything for the winter months. Some people use a bee cozy wrap, thick insulation, bubble wrap, tyvek wrapping, or tar paper. The University of Minnesota Bee Lab recommends running all hives at 3 deep (10 frames) with tar paper and a top entrance. They are agnostic about a bottom entrance. Some say to close it entirely. Some say to leave it wide open with a mouse guard.

They make the 3 deep recommendation because we have such long winters. If you live in zone 6 or warmer, you may be able to get by on 2 deeps.

They recommend the tar paper based on studies that showed honey bees greatest survival versus food use came from the windbreaking action of a thin layer such as that provided by tar paper.

We read through some really intense and fantastic studies that put honey bees into freezers for months and evaluated their survival. When we find these studies again, we will provide the links here. The largest and most thorough study basically said that insulated hives are better for honey bees than non-insulated hives…but they had a few issues. They provided for more movement, resulting in more food usage and eventual starvation. The insulated hives did not prevent the hive from cooling to external temperatures but did slow the heat loss and solar heat gain. The bees were free to move more and that was a good thing, allowing them to reach all their honey stores. But again, since they moved more, they ate more and generally did not have adequate supplies for the winter. With more boxes/frames, this might be avoided.

Since they were slower to experience temperature changes, they reasoned that many northern bees would miss the few warm days in early spring when cleansing flights are possible if they were in insulated hives. This may or may not be the case.

Those bees that survived in insulated hives, came into the spring with bigger, stronger populations. This often resulted in starvation. Our weather does not get reliably warm until May. We have very few blooms (thank heavens for trees like alder, hazel and willow!) and the bees have a hard time flying in the frozen temperatures. So a big colony is hard to feed and generally collapses. This may be different in your area. If your winters are short and your plants start reproducing early in spring, then a lightly insulated hive just might make your colonies roar into action each spring.

The insulated hives generally resulted in more Nosema infections because there was not adequate beehive ventilation for winter and that when offered adequate ventilation (via a top entrance and bottom entrance) much of the insulative benefits were lost.

Regardless of insulation, the bees worked hard to maintain a core temperature throughout the cluster – with, of course, the outer layers of the cluster being colder and the sides of the hive always matching the external temperature.

Please keep in mind that a full 10 frame hive does provide more insulation from the external frames compared to bees clustering in an 8 frame hive.

Here are a few sources on the science behind bee wintering:

We have created our strategy based on information from the U of M bee lab, the sources linked above, and numerous studies we were not organized enough to save!

We chose not to insulate our hives. In the future, we will likely experiment with the styrofoam hives, thick walled tree trunk hives and other configurations. We will always report back on our results.

We chose to wrap our bees in corrugated signs – old political signs work great for this. We reasoned that since the wrap was acting mostly as a windbreak, a solid piece of corrugated board was just as good as the tar paper, and less of a hassle.

We cut our signs to fit a 3 deep configuration. Then we tape them together with gorilla tape and affix them to the hive. When not in use, they fold flat for easy storage.

Sorry for the wind in this video. Our apiary is in the sand plains and it is windy!

Our steps for wintering bees in northern climates – beehive winter protection

  • Treat for mites throughout the growing season
  • Add mouse guards when the leaves start to change color
  • Feed sugar syrup if the colony is light
  • Remove all sugar feeders when weather drops below 50F
  • Use our corrugated political sign “jackets” as a beehive cover
  • Add a “fondant” sugar cake to the top frames (on newspaper, on the frames, right below the cover)
  • Use a cover with a notch for upper entrance
  • Cut a flap into the bee wrap jacket to allow access to the upper entrance
  • Place a 2″ thick piece of Styrofoam insulation above the cover and under the lid
  • Strap the hive to the cinder blocks with a ratchet strap (to protect against wind and animals.)

Honey bees will not touch the sugar cake unless they have moisture to eat it. It is solid/hard and over the winter as their warm air condenses down the sides of the hive, this will provide moisture for them to consume their honey and the sugar cake (if they should need it when they get up to the top.)

Our sugar cakes do not go across the full span of the hive. There is 1/2″ gap around the cake that allows air flow and bee movement. We also cut off all that extra newspaper you see in the photo. It is there for easy lifting of the cake and for placement onto the frames, but it gets trimmed.

We make our sugar cakes the easy way. We fill a bowl with sugar and then mix in a little water until it is compressible like a dough. This is very little water. Then we put newspaper into an extra large cake pan (that just so happens to be about the size of the hive cover) and press the sugar dough into it. You can not see the depth in this photo but it is about 3/4″.

We then set the sugar cake in the porch to dry. Many people dry it in a warm oven. It is essentially a sugar brick, and it’s impossible to mess up.

This goes on the top of the frames, right under the cover.

The cover goes on next, then a 2″ piece of styrofoam.

We care very careful to make sure the top entrance and bottom entrance are on the same side of the hive (for us this is the east – our winter winds blow from the north and the west, and our hives face East to avoid these winds.) Putting the entrances on the same side creates a chimney effect, meaning the air flow should go straight up, as opposed to across and through the bees.

Our winds will be between -20 and -60F throughout much of the winter. It’s imperative that we keep the entrances on the same sides.

The Styrofoam top does not “keep” any of the heat. It does slow some heat loss, but there is an entrance right near it, somewhat negating any benefit. It’s a vapor barrier. This is supposed to prevent the bee heat from condensing on the cold surface of the cover. Instead, the heat should condense on the sides of the hive and drip down the sides, rather than raining from the top.

Honey bees require this condensation to survive. They can not digest honey without water, and they can not go out and get water in the winter.

There is a very thin line between too much and too little ventilation. Bees need air to breathe. They also need to conserve and save as much of their warmth as possible.

Too little ventilation can cause excess condensation, molding and nosema infection. Too much can take away all condensation and leave the bees starving and/or with dysentery. Oh the struggles!

Wind whipping through the hive is deadly. Bees manage this by sealing the boxes together with propolis. We ruin this by popping the boxes and frames. We help by stopping our inspections in advance of cold weather and wrapping the outside.

We protect them from outside invaders – mice, raccoons, bears. We ensure their ability to get oxygen and to fly out for cleansing flights by providing an upper entrance. And then we wait.

We hope that our winters do not have fast temperature fluctuations. Slow and steady helps the bees adapt. We hope for a short winter and adequate precipitation so flowers and trees can start growing as soon as possible. We hope our bees had a strong enough queen and worker population to weather the long cold days ahead.

We never know until spring. All we can do is prepare and wait. We wish you luck as you prepare your bees for winter.

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