I have hesitated to write a page on wintering bees and so far had resisted the temptation because wintering is so tied to locale. But I get questions all the time and wish to state what I think on many of the issues. So please read all of this with locale in mind. I will try to cover what I do in my locale (Southeast Nebraska) in detail and why I do what I do, but that does not mean it is the best for your locale or that some other methods might not work in other or even my location.
I will break this down into topics or manipulations that are commonly discussed whether I do or do not do them.
Another thing that matters is the race or the breeding. Mine are all mutts, but they run from brown to black and are Northern bred survivor stock.
I'll break it down by items and actions:
Typical questions are what to use and when to use them. I have only upper entrances so mouse guards are not an issue. Back when I had lower entrances I used 1/4" hardware cloth for mouse guards, but I might consider, if I were still using lower entrances, a popular device here in Southeast Nebraska. The device is a 3" to 4" wide piece of 3/8" plywood cut to fit the width of the entrance and three 3/8" laths cut to the 3" or 4" width of the plywood. This slides into the entrance reducing it to 3/8" and forming a baffle so that the wind doesn't blow in. People who use it say there is no problem with mice as the 3/8" gap being several inches long seems to deter the mice. As far as when, I'd try to get them on by or shortly after the first frost. Here we get some warm weather after the first frost, so the mice usually don't move in until it stays cold for several days. You want them on before then or the mice may already be in the hive. The other nice thing about the "baffle" type of entrance reducer/mouse guard is you can leave it in all year around and you don't have to worry about remembering to get the mouse guards on.
I don't use excluders, but when I did, I would remove them before winter as they can cause the queen to get stuck below the excluder when the bees move up. The excluder will not stop the bees from moving up, but will keep the queen from joining them. You can store it on top of the inner cover or at the top of the hive I you like, but don't leave it between any boxes.
Screened bottom boards (SBB)
I have these on about half of my hives. If the stand is short enough and enough grass blocks the wind, I sometimes leave out the tray, but usually I put the tray in. Some people in some climates seem to think it's good to leave them open year round, but I don't think it works well in a cold windy climate like mine. I also don't think the SBB helps much with Varroa, but it does help with ventilation in the summer and it keeps the bottom board dry in the winter. On the other hand a solid bottom board can double as a feeder and a cover.
I don't. I tried it once, but it seemed to seal in all the moisture and cause the boxes to remain soaking wet all winter, so I quit doing it.
I put my hives on stands that hold two rows of seven (eight frame) hives. Basically they are eight foot long treated two by fours with four foot ends on them. The rails (the eight foot long pieces) are such that the outside ones are 20" from the center and the inside ones are 20" from the outside. This allows the hives (which are 19 7/8") to be all the way forward in the summer to maximize convenience of manipulating them, and all the way back in winter to minimize exposed area. So during the winter 10 of the hives are touching on three sides and the four on the outside ends are touching on two sides. This minimizes exposed walls. Sort of like huddling together for warmth.
Contrary to popular belief, winter feeding honey or syrup does not work in Northern climates. Once the syrup doesn't make it above 50° F (10° C) during the day (and it takes a while to warm up after a chilly night) the bees won't take it anymore anyway. The time to feed if needed is September and if necessary and if you're lucky you may be able to continue into October some years. The questions always seem to be what concentration and how much.
When feeding honey, I don't water it down at all. Watered down it spoils quickly and I can't see wasting honey. When feeding syrup (because you have no honey) the concentration should not be below 5:3 nor above 2:1. Thicker is better as it will require less evaporation, but I have trouble getting 2:1 to dissolve.
How much is not the right question. The right question is "what is the target weight?" For a large cluster in four medium eight frame boxes (or two ten frame deep boxes) should be between 100 and 150 pounds. In other words if the hive weighs 100 pounds, I might or might not feed, but if it weighs 150 I won't. If it weighs 75 pounds I'll try to feed 75 pounds of honey or syrup. Once the target weight is reached I would stop.
My management plan is to leave them enough honey and steal capped honey from other hives if they are light. But some years when the fall flow fails, I have to feed. I like to wait until the weather turns cold before harvesting as it solves several issues. 1) no wax moths to worry about. 2) the bees are clustered below so no bees to remove from supers. 3) I can assess better what to leave and what to take as the fall flow did or did not occur. Another option for a light hive, if it's not too light, is to feed dry sugar. The down side is that sugar is not stored like syrup, so it's more of an emergency ration, but the up side is you don't have to make syrup, buy feeders, etc. But it not being stored is also the up side. If they don't need it, you don't have syrup stored in your combs. You just put an empty box on the hive with some newspaper on the top bars and pour the sugar on top of the newspaper. I wet it a bit to clump it and wet the edge to get them to see it is food. If the hive is only a little light this is nice insurance. But if it's very light, I think they need to have some capped stores and I'd feed them honey or syrup.
It seems to be a common misconception that feeding syrup can't hurt and people often feed just to be feeding or because it's fall and it's "what you do in the fall". But syrup DOES hurt in several ways. It may be better than starvation, but if they don't NEED it, then it is far better to not feed sugar syrup.
Another issue, while on the subject of feeding with no real purpose in mind, is that people will feed incessantly in the fall until there is no where left for the bees to cluster and the humidity in the hive is high from all that syrup that needs to be dried. Then they don't understand why they lose hives in winter.
Bees need to cluster in empty comb where the bees can climb in the cells to compact the cluster. The cluster is often compared to a "ball of bees" but people forget that there is comb between those bees and to be a dense cluster they climb into the cells, which they cannot do if they are filled with syrup.
A solid bottom board can be converted to a feeder. This makes sense to me because feeding isn't my normal management plan, leaving honey is. Why buy feeders for all your hives if feeding isn't a normal situation? But if I need to feed, I don't have to buy a feeder for each hive. They hold about as much as a frame feeder. Around here candy boards are popular, but the dry sugar on top is easier as you don't have to make the boards, and make the candy. You just use your standard boxes and sugar. I've also been known to spray syrup into drawn comb to give a light hive to get them through.
Sometimes I insulate the tops and sometimes I don't. I gave up insulating anything else. I think it's a good idea to insulate the top, but I just don't always get it done. Since I run a simple top with a top entrance, when I do insulation it's just a piece of Styrofoam on top of the cover with the brick on top of that. This will reduce condensation on the top, as does the top entrance. Any thickness of Styrofoam will do. The main issue is condensation on the lid. When I have tried insulating the entire hive the moisture between the insulation and the hive became a problem.
I think this is essential to reducing condensation in my climate. It was not necessary when I was in Western Nebraska which is a much drier climate. It doesn't have to be a large top entrance, just a small one will do. The notch that comes on the notched inner covers is fine. This also provides a way for the bees to exit for cleansing flights on warm snowy days when the bottom entrance (which I don't have) would be blocked with snow. I have only top entrances and no bottom entrances.
Where the cluster is
Usually around here it's in the top box going into and coming out of winter, with or without a top entrance. Sometimes it's not, but that seems to be the norm, despite what all the books seem to say. I leave them where they are and I don't try to make them be where I think they should be. Usually they spend the entire winter there.
This question comes up a lot. I used to combine weak hives and I seldom lost a hive over winter. However, since I started trying to overwinter nucs I've realized how well a small hive takes off if it does make it through the winter. So I've overwintered much smaller clusters. Also if you have local queens, instead of southern queens, they do better as well as the darker bees overwintering on smaller clusters than the lighter colored bees. So, while I've never seen a softball sized cluster of southern package Italians get through the winter, I've seen that size of feral survivor stock, Carniolans and even Northern raised Italians make it. This is actually going into winter on a cold day (tight cluster). There is some attrition in the fall, and if they are this size in September and there is no flow and they are rearing no brood, they probably wouldn't make it. A strong Italian hive going into winter would be a basketball sized cluster or more, while Carniolans or Buckfasts are usually more like soccer ball sized or smaller, and feral survivors tend to be even smaller.
I do like them on all the hives. On the strong hives they create a traffic jam in the case of a robbing frenzy which will slow things down, and on a weak hive they create a smaller space to guard. On all the hives they create less of a draft than a wide open entrance. In fact when I have forgotten to open up the reducers in the spring, even the strong hives with the traffic jams because of it seem to do better than the ones that are wide open. I do try to remember to open them up on the strong hives for the main flow.
I have, in recent years, started feeding pollen in the fall during a dearth so they are well stocked with pollen going into winter and so they have one more turnover of brood before winter sets in. There is no point in doing this while real pollen is coming in. I feed real pollen if I have enough. I have sometimes mixed it 50/50 with substitute or soybean flour when I'm desperate and don't have enough. I never mix it at less than 50% real pollen. You can trap this yourself or buy it from one of the suppliers like Brushy Mt. I feed it in the open. I put it on a SBB on top of a solid bottom board in an empty hive. This would be in September usually.
Some people use straw bales to get a windbreak. I hate mice and they seem to me to be mouse nests waiting to happen, so I don't. But if you kept them back a ways maybe they would work. I suppose one could use corn cribbing or snow fence for a wind break as well as any kind of privacy fence. Mel Disselkoen uses a ring of sheet metal around four hives to make a windbreak for them. This looks like a good setup to me but requires buying the metal and storing it during the rest of the year and then setting it up again in the fall.
I find that eight frame boxes overwinter better than ten frame boxes. The width is more the size of a tree and the size of a cluster, so there is less food left behind. This is not to say that you can't winter bees in ten frame boxes, just that they seem to do slightly better in eight frame boxes.
I find that medium boxes overwinter better than deeps as there is better communication between frames because of the gap between the boxes. If you picture what is in the hive when the bees cluster in the winter there are combs making walls between parts of the cluster. With a sudden cold snap a group of bees often get trapped on the other side of a deep frame when the cluster contracts as they can't get to the top or bottom and over, where with the medium the cluster usually spans the gap between the boxes providing communication between frames throughout the hive. Again, this is not to say you can't overwinter them in deeps, but only that they seem to do slightly better in mediums.
I find they winter better on narrow frames (1 1/4" on center instead of the standard 1 3/8" on center or the 9 frame arrangement in a ten frame box which is about 1 1/2" on center) because it takes less bees in the late winter to cover and keep the brood warm than it does with larger gaps. Again, this is not to say you can't overwinter them on 1 3/8" frames, only that they seem to do slightly better, build up earlier, get less chilled brood and less chalkbrood on narrow frames.
I have tried overwintering nucs every winter since 2004. I can't claim to be good at it, but when I get nucs through they are my best hives the next year. I've tried many things from wrapping, huddling, heating, feeding syrup all winter etc. I've come to these conclusions. First, wrapping just made them too wet. Feeding syrup all winter did also. Insulating top and bottom and huddling were helpful. A heater if not too hot, down the middle of this arrangement was helpful, except every year someone unplugs it during the coldest spell, so it really hasn't helped. My nucs are a bit backwards of most as mine are combines of mating nucs rather than splits from my strong hives or requeening and splits from my weak hives. I've concluded that one mistake I've been making is I need to combine them soon enough for them to get reorganized as their own colony before the cold weather sets in. Which means about the end of July or the first of August. This also lets them get some stores put away and arranged the way they want. But assuming you're making splits of your weak hives and requeening them, the same rule holds true. You want them to have time to get organized as a colony. I'm liking the sugar on top more and more for these as feeding syrup has the problem of too much moisture. But if you feed early this isn't so much of a problem. Rather than spend a lot of time making special equipment for overwintering nucs, I think it's more practical to figure out how to overwinter them in your standard equipment. Granted, this makes more sense when your typical box is the size of a five frame deep nuc (my eight frame mediums are exactly that size), but I hate having a lot of specialized equipment around when I can have equipment that is more multipurpose. My bottom board feeders work well for wintering nucs as you can stack up the nucs and see if they need to be fed and feed any of them without unstacking them.
I've tried overwintering a queen bank. I have not had really good success but these are the things that helped. You have to keep it warm enough to keep them from clustering or they will contract to the point that many of the queens will die. The best way I found to do this was a terrarium heater under the bank. You also have to repopulate the hive part way through the winter. This means either sacrificing one of the nucs or stealing some bees from a really strong hive. If you pull out a frame that is well covered in bees, but not too close to the center you have a better chance of NOT getting the queen and then you add that frame to the queen bank. If you get half of the queens through the winter, I think you're doing well. But if you do, you have a bunch of queens in the spring for queenless hives, splits and for selling at the time when the demand is high.
I have not tried it other than the observation hive I typically winter. I have corresponded with many people who have tried it and it is far trickier than one would think. Bees need a cleansing flight now and then so they need to be free flying. They need temps down around 30° to 40° F (-1° to 4° C) to keep them inactive so they don't burn up all their stores and burn out from activity (inactive bees live longer than active bees). Ventilation and keeping bees cool enough seem to be the bigger issues with this than keeping them warm.
Wintering observation hives
I have wintered an observation hive many times. The issues are to make sure they are strong enough going into winter. Have some way to feed them syrup. Have some way to feed them pollen. Don't' over feed the pollen. Make sure they are free flying (check the tube to make sure they haven't clogged it with dead bees and pollen). No, they won't all fly out and die because they are warm and confused about the weather outside. They are quite aware of the weather outside. If they get too weak in the spring you may have to boost them with some bees. A handful or two of bees in an empty box that is connected to the tube will usually result in those bees moving into the hive without you having to take it outside and open it.
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