How I overwintered ten out of ten

I have been thinking about this post for about a month, but I didn’t dare write it until spring was here for sure. But on Thursday, when a fur-coated bumble bee alighted on the patio and a bee fly examined my shoe lace, I knew I could call it.

To be more specific, I went into September with nine Langstroths, one top-bar, and three nucs. Today, with April just a breath away, I still have nine Langstroths, one top-bar, and two nucs. Not only are my colonies still alive, they are bursting at the seams. Bees are pouring through the entrances and climbing up the walls. I am elated.

Those of you who have read my blog for a while know that “overwintering” is my main honey bee interest. I usually manage to overwinter 60-80 percent of my hives. But this year I decided to “pull out all the stops.” I tried everything I could think of to help the bees make it through the winter.

The result, of course, is no controlled experiment or repeatable design. In fact, there are so many variables it would strain the organizational capacity of Excel. So all I can do is tell you what I did and why.

Before reviewing my steps, I’ll give you a quick overview of my local climate. In one of my very first posts on this blog I wrote that “all the challenges are local” and I still believe that. Beekeeping is not performed in a vacuum, and your local climate plays an immense role in the life of your bees.

I live in western Washington in the middle of the Puget trough. The word “trough” reminds me of water, and that pretty much sums it up. It rains nearly constantly in the nine-month period from September through June. It doesn’t add up to a lot—annual averages are about 51 inches—but it rains a little bit all the time. The three-month period of July, August, and September is hot and dry, dry, dry. No rain. Zilch. Nada. Everything is crisp.

Although I live at 47°N latitude, I am in USDA hardiness zone 8, which means it doesn’t get very cold in the winter. It dips down in the teens and twenties, but doesn’t stay very long. We get snow in the lowlands, but only two or three times per year. The average winter day is 40°F and raining.

So here are the steps I took to overwinter my bees, beginning in June 2010.

• By June 30, all honey supers were off my hives.

Comment: I live adjacent to a 91,650-acre state forest and the only farm crop in the immediate area is hay. So my bees forage almost exclusively on spring-flowering trees and roadside weeds. By the time the hot dry months arrive, there is almost no forage to be had. Whatever honey I get accumulates from April until June.

• During June I collected enough swarm cells to begin four nucs.

Comment: I wanted to carry one or two extra queens into the winter in case one of my colonies went queenless. So I started four nucs with swarm cells. Three of these produced viable queens. By fall I had three healthy nucs “just in case” something went wrong with one of my colonies.

• In August I treated for mites.

Comment: First off, I never use any conventional pesticides in my hives. However, if mites are a problem I use one of the all-natural products made from thymol (an essential oil of thyme) or formic acid (an organic acid.) Unlike conventional pesticides, these are difficult and time-consuming to use.

This year I used ApiLife Var (a thymol product) which requires multiple applications over the course of three weeks. Honey supers cannot be in place. But it is the timing of treatments that is important for overwintering.

The thymol and formic acid treatments should be used when little brood is present—so later is better. But you want to treat summer bees for mites, not winter bees*—so earlier is better. You have to make a judgment call. In this case, I set aside August for mite assault.

*In case I lost you here, summer bees live an average of 4-6 weeks. Winter bees can live many months—all the way into the following spring. If you treat for mites after the winter bees are born, it is too late to protect them from viruses carried by mites. In other words, a late mite treatment will still kill the mites, but only after the viruses have been transmitted to the winter bees. This way, you have gained very little. You need to kill mites in the summer bees so the hive is relatively free of viruses when the winter bees are born.

• In September, I checked the hives for honey stores. Any hives that appeared to be short on honey were given some extra frames reserved from the harvest in June, or given sugar syrup mixed with Honey-B-Healthy, or both.

• Entrances were reduced on all hives to protect them from robbing and yellow jackets.

• All Varroa drawers were removed from the screened bottoms to provide maximum ventilation.

• The slatted racks remained in place in the Langstroth hives all winter long.

Comment: I consider slatted racks basic equipment in Langstroth-style hives, so I never remove them in any season. In summer they provide a place to hang out during hot muggy days, and the queen tends to lay eggs further down on the brood frames–apparently because this area is no longer near the “front door.”

In a traditional winter hive with the Varroa drawer in place, the slatted rack adds an insulating layer of air between the brood nest and the Varroa drawer. This will not exist in the same way with the Varroa drawers pulled out. However, during cold snaps (see “weather forecasts” below) –or other times when the Varroa drawers are in place–the slatted racks again provide a “dead air” space that helps to keep the bees a few degrees warmer.

• Each hive was topped with a quilt box outfitted with four ventilation holes and filled with wood chips.

Comment: Of all the changes I made, this one had the most visible result. In prior years I always had condensation dripping down on the bees from the inner cover. This year none of that moisture reached the bees. They were dry and happy all winter long.

Originally I had anticipated having to change the wood chips every couple of weeks. As it turned out I never changed the wood chips. The ventilation holes seemed to play a big part in preventing the chips from getting soggy. About one-inch of the two-inches of wood chips got wet in each hive.

In my opinion, the combination of more ventilation and less moisture accumulation were the two most-important changes I made to the hives.

• As always, I checked my hives every day or two. I wasn’t looking for anything in particular except for fallen trees or bear damage. Usually I just walked by each hive and flicked the dead bees off the landing board.

• It was on one of these routine checks that luck played a big part in this year’s success. On December 15, just as I was about to flick a dead bee off of hive #2, I realized it was the queen. Darn! I knocked on the hive and it was loud and robust. I examined the queen: she looked freshly dead. So I put one of my nucs in a deep brood box and, using a slit piece of newspaper, combined it with hive #2.

Comment: I still haven’t opened this hive except to add feed. But when I get near it I can hear it roar like a caged lion. Luck definitely played a role here, but pre-planning gave me the queen I needed to keep the colony alive.

• I paid attention to the weather forecasts all winter long. Three times the temperatures dropped into the twenties for an extended period (more than a day or two). In each of these three cases, I inserted the Varroa drawers under nine of the hives and put both the nucs and the top-bar hive in the garden shed.

Comment: My husband convinced me the hives would stay a lot warmer with the bottom drawers in, so in very cold weather I gave them a little help. This compromises ventilation, however, so as soon as the temperatures got back into the 30s, I removed the drawers again.

The nucs were small, so I put them in the shed which is about ten degrees warmer than the outside. The rest of the time they were outside, stacked with double-screen boards between each.

I coddled the top-bar hive because it was a July swarm that moved in by itself, and it couldn’t possibly have had a lot of stores. So, when the nucs went inside, the top-bar hive went in as well. But it, too, came out as soon as the temperature climbed above freezing.

• Right around the end of December, I added a feeder rim to each hive. I placed it just above the top brood box, but underneath the quilt box. I added sugar patties to each hive during January and February.

• In mid-February I began adding pollen substitute to the sugar patties. I continued feeding pollen-enriched patties until now.

Now that it is spring and my hives are boiling over with bees, I’m already worried about swarming. Wouldn’t you know it? If you succeed at one thing, you’ve got to worry about something else.

Rusty
HoneyBeeSuite

Comments

steve
Reply

I’m learning a lot by reading these posts. You folks are great. I’ve one hive and am going into my second season with them.

I’m in northern Wisconsin where it gets cold. I’ve more questions then I can fit here but my experience of yesterday makes me submit this one.

It warmed into the low 50′s F yesterday and cleansing flights were the order of the day. I found a number of workers scattered around in the snow curled up motionless.

I picked up four, cupped them in my hands and breathed on them. After a bit they all got busy again. I put them by the hive entrance and they went in, I think. There was a lot of action there.

Understanding that cyroprotectant chemistry comes into play I am wondering if there isn’t something I can be doing in the fall to either move the hive to a warmer location or in some way give these little folks a better chance of survival.

Any thoughts?

Steve

Rusty
Reply

Steve,

One of the reasons bees fly out and die is that they believe it is warmer outside than it really is. Honey bees need temps in the high 50s to fly safely. It was probably that warm around your hive entrance if it was in the sun, or if warm air from inside the hive was leaking out. So the bees fly out to do cleansing flights but then get too cold to return. Just like a human jumping into icy water, they only have a short time before they are too cold to move. Usually this happens to a small number of bees and it is nothing to be especially concerned over.

However, keeping hives too warm by adding heat can have adverse effects on a colony. Hives that have been kept artificially warm with heaters or light bulbs are apt to have high mortality because the bees are lead to believe that the outside is warmer than it actually is. They tend to fly out and die. It is best to remember that bees do really well in the cold. Bees that don’t make it over the winter usually have a problem like disease, mites, or a lack of food. A good strong hive seldom dies because of cold weather unless you are very far north or unless the bees get wet.

Ulubees
Reply

Hi Rusty,
Thanks for the great information. I am caring for bees in a similarly wet and fairly mild climate. How many lbs. Of honey do you leave the bees for overwintering?

Rusty
Reply

I have never actually weighed my hives. I like to see at least 8 of the topmost 10 frames filled with honey. If I can barely move it, that is good.

Nancy
Reply

Hi, Rusty,

I keep re-reading this and the post about preparing hives for winter. You said that bees cannot fly at lower than 50 degrees. During these cool nights, sunny days, I find bees that seem to have “fallen asleep” on a sunflower late the previous day, and as the sun hits them, to “wake up” and begin harvesting again. Suppose if it got cold enough, they would just have died during the night. How cold would it have to get?

My biggest worry is a weather phenomenon that we have seen in recent (otherwise mild) Winters: a reversal of the normal diurnal cycle. A cold front moves in fast and temperatures drop during the day. A friend has pictures of bees which died going in and out of cells right in their hive (which he lost). So it wasn’t cold enough early in the day for them to get into a cluster, and then it was!

If it got cold while the sun was high, a lot of foragers would be caught out.

Have you done a post on temperatures specifically? Or do you know of a source? Thanks!
Nan

Rusty
Reply

Nan,

Somewhere in a massive pile of journal articles and research reports I may have something on temperature that gives specifics. But offhand, I don’t know. I will put it on my list of topics. I do know that honey bees are more temperature sensitive than some other species. Both bumble bees and mason bees, for example, can forage at much lower temperatures than honey bees.

Ron
Reply

Rusty,

Very good article. This is exactly the type of data I would like to prove true by running side-by-side tests of same type bees and strength of hives, 5-10 hives with slatted racks, quilt box, etc. versus 5-10 hives without. I noticed you had a couple that needed feeding to go into winter. I can only imagine what the result would have been without the slatted racks and quilt boxes. Those needing feed not being fed plenty early in the fall to fan the high moisture feed down to the wax capping moisture would have just been trading feed for nosema, and high moisture in the hives, which is what kills and weakens bees. I would guess that out of the 10 that survived you had little to no dysentery because the hives were kept dry, fed early enough, and provided good ventilation and a way to keep excess moisture out of the hive.

I have seen time and time again beekeepers, if they can be called beekeepers, in moderately cold winters (where temps drop down below 15 degrees for more than a week) feed bees so late the bees can hardly take it down let alone fan it down to the proper moisture to cap, and they scratch their head and wonder why their bees died through the winter.

I remember seeing in the eighties a yard of 40 commercial beekeepers hives in which 19 of them survived a brutal winter in northern ND. Extremely good considering they were abandoned not wrapped, treated or anything. Hence my belief in the truth that cold does not kill bees, moisture does. A hive with plenty of stores of honey, pollen and a good queen, good ventilation, 10 out of 10 is not all luck, it is good beekeeping and knowing the wants and needs of the bees. It tells me you put the needs of the bees above the what’s easiest for the beekeeper. Good Job. Keep up the good articles, and have another prosperous and good year. Merry Christmas and a Happy New Years to you and all those who contribute and learn from your research and articles. Thanks Ron

Rusty
Reply

Ron,

Thank you so much for your high compliments. You pretty much sum up what I believe are the problems with overwintered hives. In my opinion, moisture is the number one winter problem, hands down. Wet bees are dead bees.

Merry Christmas to you, too, and a healthy and prosperous New Year to you and your family.

Thanks for writing and thanks for reading!

Bob W.
Reply

Rusty,
I almost gave up beekeeping after 5 years. The spring was always a tramatic time for me. How many colonies had I lost this winter? I’m on an island in Lake St. Clair, a few miles North of Detroit, Michigan.

As an architect I decided to come up with an insulation system that would remain on the hives all year round. (because I am too lazy to put it on, take ioff, store it, etc.) In the fall of 2010 I installed permanent insulation on 1 of my 4 hives. Only the insulated colony survived that winter. I bought two replacement packages. The following fall I had 3 hives and insulated the two that still needed it. All three survived the winter. In the summer of 2012 one swarmed into an old hive stored nearby. I insulated that. As of yesterday, March 10, 2013 all four colonies are doing fine.

I do not feed or medicate any of my bees. I do as little management as possible. My primary goal is pollination, not honey production. I agree somewhat with the above comments by a reader about not overprotecting the bees because that could lead to weakened genetics in the pampered survivers, however, when I compared the natural protection provided to feral bees in trees to the miserable 3/4″ thick wood we were giving them for protection I decided my managed bees deserved a fighting chance at least equal to the feral colonies.

The year-round insulation system I came up with is fully DIY with materials from any home improvement store. It costs about $30 per hive and so far has lasted 3 years and probably is good for 5 years, maybe more.
I have details on my website at http://bees.stewartfarm.org.

I like the thoughts expressed about the quilt box. I don’t think I have any moisture problem, but, I’m going to look carefully for any indications of moisture over the winter and maybe try the quilt box.

Thanks for all the good discussion.

Bob W.

Rusty
Reply

Bob,

Amazing how one change can make all the difference. I agree that many of our problems are due to the flimsy nature of our hives, and I compared a tree to a Langstroth in Ventilation Part 1: A hive is not a tree.

Your site looks interesting! I will spend some time with it as soon as I have a few moments. Thank you for all the info.

Helen
Reply

Hi Rusty,

We just installed our first 2 packages. Magical.

As usual, with my free time, I have been roaming HBS and have been reading your thread on ventilation and insulation. I wonder, did you read Bob W’s website on his permanent hive insulation at Stewart Farm? If so, what did you think? It would not be out of laziness or lack of management responsibility that I would do this. It just seems to make sense. You successfully over wintered your bees by checking weather forecasts, moisture quilting, adding food stores, etc, but it seems like we could make it easier for our house guests and ourselves if we provided them with better insulated homes in both summer and winter and also would take a lot of the guesswork out. It amazed me that he had so few dead bees and that they consumed so much less food. Any thoughts?

Rusty
Reply

Helen,

If you want to try the permanent insulation, by all means, go ahead. Just remember that insulation is one piece of the overwintering puzzle. There is still ventilation, condensation, food stores, diseases, pests, predators, mites, hive beetles, viruses, dysentery, and on and on. Conditions are very local, and one year is very different from the next. I would never put too much hope in one aspect, but try to do the best with as many aspects as you can think of. After your first winter, you will have a better appreciation of how difficult it can be.

Robert Williams
Reply

This is Bob Williams, designer or the Stewart Farm Year-Round Insulation system. Rusty, you are right on track about winter survival being much more than the insulation alone. Here’s a few quotes from the powerpoint I do on winter survival.

“A colony of bees is able to survive cold temperatures for extended periods of time if they are healthy, are of sufficient size, have enough food, both honey and pollen, can get to the food and are not exposed to excessive moisture.”

winter prep
“Protected from strong winds
Shrubs, fence, straw bales, other windbreak
Straps, bungees, props, top weights
Remove dead trees or branches
Critter protection
Bear fence
Mouse guards
Bungee the supers”

“Strong, healthy colonies
Young, productive queens
Brood nests at the bottom
Pollen near the brood nests
Lots of honey, fairly centered, above the brood nests
Frames aligned full height (all 9’s)
Start early (Don’t disrupt the bees plans for the winter)”

“All excluders removed
Lower entrance openings to be turned up
Mouse guards in place
Upper entrances / ventilation open
Insulate ”

other options
“Fall feeding
Provide absorbing material under the top cover
Leave more space between the center frames
Stack the honey frames and install solid wood dummy frames on the sides
Winter feeding if the conditions are right”

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