After the disastrous 2013-2014 winter with its -20F temperatures I resolved to do better in the 2014-2015 winter season. While performing the clean up of the many 2013-2014 deadouts I tried to isolate the root cause for each hive failure, whether it be starvation, moisture issues, mites, or air leaks. The vast majority were simple cases of starvation; insufficient food stores to carry the hive through the nectar drought that lasts the 7 months from late September until mid April. In the summer of 2013 I had started a number of new hives in late June. These hives were especially hard hit, because of the simple reason they did not get to store honey during the June honey flow. In this area the honey flow is primarily in the June through mid July time frame. I saw no cases of mite infestation or moisture issues. In all my hives I have a one inch diameter air exchange hole on the downwind side of the upper brood chamber.
To address the starvation situation I decided on two actions. On newly started hives I put them on a 1:1 syrup supplemental feeding at the beginning of August. Then after the late August honey harvest I put almost all other hives on a 2:1 syrup supplement to ensure they had the chance to fill the brood areas with winter stores. Sugar was running about $20 per 50 lb bag. I figured it was better to feed each hive 25 lb of sugar ($10 worth) than having to buy a $85 package. Little did I know package prices would increase to about $100 this spring. Nine hives received no supplemental feeding as a control or comparison point.
There was also the question of hive wrapping. Previously I had never wrapped any of my hives. Many club members are proponents of hive wrapping. Articles in American Bee Journal and Bee Culture are evenly split between proponents and detractors. At the last minute I decided to wrap 50% of my hives with BeeCozies. The Bee Cozy is an easy to install insulation blanket/wind break.
In September I culled three (3) weak hives and combined the bees and brood with other hives. I had not done this the previous year. I was left with 30 hives. Almost immediately one of the weaker hives was robbed out. Down to 29. I then did a quick and dirty analysis of each hive; grading them based on the number of frames covered in bees. I classed the 29 as:
Six hives were sheltered in an unheated building. I wrapped 12 hives with Bee Cozies in November when flying had declined to a minimum. All hives are in somewhat sheltered areas; either trees to the north or inside the building.
Four (4) of the hives were topbar hives and twentyfive (25) Langstroth hives. Of the Langstroth sixteen (16) had 2 brood chambers and 9 had 3 brood chambers.
All hives were treated with formic acid (MAQS). Italian and Carniolan hives were given a full dose. I applied a half dose to Russian based hives as a precaution based on the recommendation of two Russian queen suppliers. I did not analyze any of the hives for the presence of mites prior to the treatment. Mites tend to be a bigger factor in the second year of a hive; not the first. This would be the first winter for 28 of the hives.
As a final precaution, in December I provided each hive with “emergency” rations; either in the form of 2 pound sugar patties laid across the upper chamber frames or a sugar board with about 10 pounds of solid sugar.
Beginning in January I started monitoring the hives using a stethoscope. This was done on the 1st and 15th of the month. Sometimes do to curiosity I did extra monitoring; such as after a -10F night. By placing the stethoscope over the air vent in the upper brood chamber you can easily hear either a comforting buzz or dead silence.
The winter of 2014-2015 was gentle on the bees. The coldest temperature was only -14F instead of -20F. Also the extreme cold spells were shorter; usually only a few days in length versus a week or more in length in 2013-2014. We also had a January thaw allowing the bees to take voiding flights.
To date my winter survival has been an encouraging 86% (25 out of 29) versus a dismal 35% survival last year at this time. There is still another month to go before being out of the woods. Also, I have not yet verified the queens have survived.
Three of the four lost hives had been classed as weak during the fall inspection. I should consider tightening my criteria for culling weak hives in the fall. I made the classic error of hoping for the best. I should have combined two of these into one hive with sufficient winter stores and population. It’s probably better to sacrifice one queen than lose 20,000 worker bees.
One of the four lost hives was due to beekeeper error. I placed the sugar board above the inner cover by mistake essentially blocking the bee’s access to the sugar.
The fourth lost hive had appeared normal during fall inspection. It had been a good honey producer, but had failed to store much honey in the brood chambers. I did not detect this during my quick inspection. Based on its honey production I had decided to skip its fall feeding. Interestingly, many of the unfilled frames in the brood chambers were plastic based.
I saw no mites on the bottom boards of the four lost hives. Do I credit this to the use of formic acid (MAQS) or the fact that these were first year hives? Mites tend to reach toxic levels in the second year.
Again this year I saw no “moisture” related failures. Therefore, I believe my system of an open one (1) inch diameter hole in the upper brood box and leaving the small (one inch wide) hole of the entrance reducer provides adequate ventilation to prevent moisture problems.
All hive losses occurred immediately following one of the -10F nights.
A) Based on fall hive strength: 100% of the strong hives survived, 95% of the normal hives, survived, and 4 of 8 weak hives survived.
B) 100% of the top bar hives survived, 89% of the 3 brood chamber hives survived, and 81% of the 2 brood chamber hives survived.
C) By hive origin type: Carryover from 2013-100% survived; April/May packages-92% survived; June or later startups/requeens-78% survived; Swarm-100% survived
D) By queen type: Carniolan-100% survived. Italian-89% survived. Russian-77% survived*
*All Russian losses were due to beekeeper error or related to low population due to late September requeening of a queenless Carniolan hive
E) Wrapped hives-Three of the four lost hives had been wrapped. However, other factors were probably the reason for these hive failures. Conversely, hive survival of unwrapped hives did not seem to suffer. In my small test I would say the wrapping did little, if anything, to improve hive survival. I will monitor this again next winter.
F) Unfed hives-8 of 9 hives that did not receive the fall 2:1 feeding survived. This shows the bees do have the capability of surviving without supplemental feeding if they go into winter strong enough.
G) The bees in every hive accessed the “emergency” sugar provided above the frames with the exception of the top bar hives. In the top bar hive the bees congregate at the top of the comb, but the sugar patty is on the floor.
1) As a beekeeper I feel I did everything I could to help my bees survive the winter.
2) Fall feeding should be done on June or later start up hives.
3) The price of fall feeding is good insurance. Whether fall feeding or spring honey harvesting is a better beekeeping approach can be settled another day.
4) I continue to lean in the direction that hive wrapping is of little benefit other than making the beekeeper feel he is doing everything possible to help survival.
5) I didn’t see any disadvantage in overwintering by top bar hives other than it is harder to provide the bees with “emergency” feeding.
6) I don’t know how much of the greater hive survival was due to the more benign weather or my added precautions.
I will continue tracking my hives through next winter to try to learn more.