First, thank you to everyone who has sent me an email or a comment on the blog. I am surprised by the number of people who contacted me and greatly appreciate your kind thoughts! I hope this lack of planning on my part is something that will eventually save you from additional losses. As I write this, other commitments have stopped me from getting out to Sullivan to continue autopsying the remaining hives. I will do so hopefully next weekend.
What I believe happened
After seeing the same occurrence in the nuc and hive I did inspect, I believe these bees died from prolonged exposure to cold. Honey stores remained in both colonies. There was a almost a frame of pollen in each hive, as well.The brood in the hive appeared old. I do not remember any brood in the nuc.
Top Entrances
Since day one, I have used top and bottom entrances throughout the year. Everyone knows ventilation plays an important role in colony health and I believe having a complete top entrance creates a chimney effect, allowing air to enter from the bottom of the hive and exit through the top entrance, preventing overheating in summer and moisture in winter. In summer the bottom entrances are also open, as well as the screen bottom board (sbb) unless I have a sticky board in place during a mite drop test.
In winter, I close the bottom entrances and leave the sticky boards in place to reduce airflow through the SBB. I have always left the top entrances wide open with no additional insulation above other than the outer cover (either wooden or polystyrene). This has worked well for me in the past, though I am now thinking several of the hives I have previously lost may have been due to the similar issues. This year, I think the opening was too large and with temperatures down to -10F for several nights, I created conditions in the hive that the bees could not overcome.
Today, I went into the Westmoreland apiary and reduced the top entrances in the remaining 3 hives to about 3″. I did this by raising the outer cover just enough to place 2 strips of gaffers tape (think duct tape but 10x more expensive) over the front entrance leaving a 3″ opening in the center.I covered the sticky area facing inside the hive with a small strip of tape so not to catch any of the bees. This will minimize the top entrance and greatly reduce the heat loss from the hive. Hopefully, it does not create a moisture issue. Next season, I will also provide additional insulation, either by adding a medium filled with straw or making an insulation blanket, above the top super to reduce moisture and help prevent the freezing conditions.
Bottom Line…
I thought by following my normal entrance procedures, wrapping the hives with black tar paper to add solar gain and reduce drafts, plus for the first time, adding 270 degrees of wind breaks, I had done what was right for my bees. I was wrong. Leaving the top entrances wide open proved to be quite stupid and I think resulted in the deaths of 16 hives. As mentioned, I will inspect the rest of the dead hives. Currently, this is my theory and it was my error that caused this loss. Insert a very long sigh here… More later.
Thank you, again, for the kind thoughts and good ideas! I hope your bees are warm, content and quietly buzzin’ thinking about what a great summer they are going to have.
John,
Thank you for continuing to share this. I’ve always heard and read that cold doesn’t kill bees, cold water does. That said, I have always been concerned about just the effect you are suggesting. I have copied your inner cover front shims for a summer upper entrance, but I have a winter set with just popsicle sticks. They are in all four corners so the draft is diffuse and I hope not too fast flowing. I, too, close my SBBs with a board the replaces the sticky board. (I use recycled campaign signs.) I pull these out in the winter to see what debris there is and where the cluster is as well. My entrances are reduced, too.
Best use of campaign signs I’ve ever heard of, Rick! Brilliant!
Your conclusion may be correct, but it flies in the face of my reading and my beekeeping experience.
My hives are in the Lakes Region, and we have experienced the same blistering cold weather. Virtually all of my hives have open, screened bottom boards with slatted racks above the BB and under the two deep hive bodies. All have a three inch spacer boxes above the top deep (used for a sugar block and/or pollen patties in late winter, if necessary) with at least one, 1 1/2″ entrance hole for use in winter as a top entrance in that spacer box. Above the 3-inch box is an inner cover, a foam board (foil-covered styrofoam) and an outer cover.
About 1/3 of my hives were wrapped in black roofing paper. I have no added wind-breaks other than the natural terrain.
So, except for the styrofoam insulation above the inner cover, it sounds to me that your hives were better protected from the cold and wind than are mine. Compared to your set-up, my hives are wide open to the wind and not thermally insulated.
As of this past weekend, my hive losses are minimal and have been confined to my single, double-deep nucs (interestingly, all with solid bottom boards!). Specifically, of my 17 hives and 14 nucs, 17 hives are 9 nucs are still active.
My queens are NH, VT and Maine-raised from survivors (probably purchased from the same sources that supplied your queens) or their naturally-mated successors.
So, why the difference in results?
My best GUESS is mite levels. Specifically, I believe that my bees were stronger going in to winter than were yours because my bees were carrying a lower mite load prior to and during the goldenrod flow, and later as the winter bees settled their hives for winter. I treated for mites last fall (early September) using formic acid (known in lesser concentrations as table vinegar)(MAQS). You didn’t.
Please don’t misunderstand me. I am not happy about having to treat my bees, and would prefer to never treat. But I do not have your strength of character, and I would be devastated by losses like yours. I’m too old to re-grow my apiaries year after year from the few colonies that manage to survive untreated. So I measure my mite loads using an alchohol wash, and if any one hive is unacceptably high, I treat all the hives in that particular apiary.
“Take care of the bees that take care of the bees that go in to winter.”
There is much winter left, and my numbers could go south quickly. We’ll see. I’m still nervous about how wide open my hives are, and quick freezes after brood production ramps up are a significant risk.
But I don’t believe that cold alone was your problem. Cold bees that are healthy should cluster and make their own warmth. Bees weakened by high concentrations of verroa don’t have the same staying power.
With all that said, if my nucs make it trhrough the winter, you are welcome to one to help your rebuilding efforts, and if you breed a queen from your surviving hives, I’d happily welcome those genetics in my yards!
Thanks for sharing your experience with us.
Mark
Excellent observation, Mark! Well thought out and stated and quite possibly correct. BTW,I am thrilled your bees are doing so well here in NH!
I’ve been wondering about mites, too, so when I went out to Sullivan today to reduce the top entrances, I pulled one of the sticky boards that I placed under a hive last October. I found about 100 mites on the board. Based on the amount of honey that was left in each hive, I do not believe the bees died until mid, maybe late January (based on consumption). If that is true (and it’s an estimate on my part) that means a mite drop of about 1.2-1.3/day between the time the sticky board was added last fall and my estimate of when they died. If they died sooner, then my ratio is completely off. When I looked in the hive, many of the bees were head in cells, tails out showing starvation with honey stores remaining on the frames. Several bees were standing on cells of honey but were solo and certainly not in the cluster.
I opened 4 hives and at least 1 nuc. All showed the same signs with honey and pollen remaining in each hive. Due to the snow, me being incredibly cold with the wind howling and the fact I did not remember to look at the sticky boards until late in my lunch hour, I only pulled the sticky board of what was one of my healthiest hives last fall.
Your thoughts definitely make me wonder. There are clusters of dead bees in each hive. As one who has never treated, I always wonder if mites have taken one of my hives. I know they have before. I’m just surprised at such a huge loss in one apiary. I’ve called Mike Palmer to see what he thinks as I have no idea if mites fall off of the bees when the cluster dies.
My top entrances were not reduced at all (and I do not have a 3″ spacer box tho’ I sure will next year!) so part of my thinking is the bees would have been exposed to a very cold draft when they were near the top frames. I wonder if I can send samples to a lab?
Thank you for your incredibly kind offer of one of your nucs. I very well may take you up on it if the offer still stands come spring. I would be happy to share queens if anything survives out there as you are right, those will be some pretty tough bees, regardless if it is mites or cold! I’ll let you know what Mike thinks. It very well may be a combination of the 2. All I know for sure is I did something very wrong for these many colonies to die and I need to know why. Like you, I am too old to be able to ever recover from another loss like this again.