12/20/19 Update: You might want to look at our more updated article on wintering bees in Michigan.
It’s that time of the year again here in Michigan! In recent days we’re starting to spot a few snow flakes floating in. The past couple of weekends we were busy preparing our apiaries for another long Michigan winter. Actually the preparation begins way back in late July August, believe it or not. We’ve found the most essential criteria in wintering colonies is that they must go into the winter with low mite counts. Of course, they must also have plenty of healthy bees and food stores, but even if the hives are heavy, if they are carrying a significant mite load they will not winter well.
We’ve experimented a bit in the past trying to find a more foolproof way to winter bees here in our locality. Our batting average when it comes to wintering bees has ranged from total success (100% survival – a rare event!) to a almost total loss (10%). On average we seem to hit 70-80% success. In addition to making sure our colonies carry low mite loads, and have plenty of stores we also wrap our bees and insulate the tops. What follows is a step by step description of our final winter prep.
Step 1: Install entrance reducers. We like to do this earlier in October when the bees are not yet clustered and the probability that we’ve entrapped a mouse is really low. The entrance reducers are primarily to keep the rodents out of the hive. We like to use metal reducers, as they tend to be more effective. However, they take longer to install and we find that the wooden ones work as well, provided they are securely screwed in and not simply inserted with nothing to keep a persistant mouse from dislodging them.
Step 2. Place an insulation chamber on top of the double deeps the colonies will wintering in. This is actually something we’ve just started doing last year after hearing an old-timer at the MBA meetings talk about it. We tried this on half of our colonies last year and discovered the following March that all the colonies that had insulated tops had larger clusters. This year we decided to do all of our colonies this way. We basically use older “retired” shallow or medium supers with hardware cloth cleated on the bottom to hold in the insulation. We’re using cedar shavings for insulation. To make sure the condensation can escape we create a chimney in the middle with a section of 3 inch PVC. We place the insulation chamber directly on top of the hive, place the inner cover on top of the insulation chamber and then place a twig on top of the inner cover to make sure there is a gap for air flow once we place the outer cover on.
Step 3. Next we wrap each hive in roofing paper. We cut it down to size, wrap tight and secure the paper in place with a staple gun. The paper (at least in theory) should help warm the hive more on a sunny February afternoon and give the cluster a bit of mobility. Does it help? Seems to, though the few times in the past we’ve been too busy to get the hives wrapped we still had reasonable success. Another side benefit it is that it makes the hives a bit less visible from a distance. Once the leaves are down and the foliage all frozen away, a yard of bees even when way off the beaten path, seems to stick out like a sore thumb. Once wrapped they tend to be harder to spot, and hopefully less vulnerable to heartless human vandals and/or bee rustlers.
Step 4. Once the hives are wrapped we make sure each upper hive body has an upper entrance. This gives the bees and upper entrance if the reduced bottom entrance gets clogged with dead bees and other debris. It also provides a bit of extra ventilation to get rid of condensation.
Step 5: We tack a small wood cleat directly under the upper entrance. This makes it easier for bees to land and re-enter and also helps hold the paper up against the hive right where the bees will be going in and out.
Step 6. The last thing we do is insert debris boards under the bottoms (we used screened bottom boards) and then shove hives together in pairs on their stands. We build our stands with wolmanized 4×4’s so that there is a dead air space under the hives when they are centered side by side. During the Spring/Summers we push them apart again.
That’s it! Not much left to do again until early March when we go and see how they did.