Winter bee losses

winter clean02

We checked our hives this week. This is usual for Spring and gives us an idea of how they are progressing. Sadly we have lost two hives with a third being very weak. The fourth can only be described as being on death’s doorstep. The afternoon was spent cleaning the hives and feeding pollen patties to the two remaining weak colonies.

So it is not looking good as we begin our new season. Losing all the hives is something we were not expecting and do not want to repeat. Our neighbor also lost his four hives. So our plans to split his hives and make more are now out of the question. We hope to find some nucs available to purchase but being late for ordering will certainly complicate matters.

Some of you will be asking why they died? I will try to explain a variation of reasons why they perished. You can take some of these thoughts, parts or all of them and come to some of the same conclusions as us. Without getting the debris tested, it’s complicated and even then the results of looking through a microscope may not be conclusive. Definitely not conclusive enough to come to one sole reason for the loss.

Firstly some info to set the scene. We repeated what we do every year regarding wrapping and insulation. The hives were left with plenty of honey and three of the four were strong in population going into the winter.

All the hives were treated for “varroa destructor” mite (gotta love that name!). Each year we have alternated treatment between Apistan and Apivar to curb resistance to either one chemical. I have some doubts about the effectiveness of Apistan, which we treated with this year. We have had more success with Apivar. All the hives were alive when inspected in February. This was when extra sugar patties were added as a precaution, even though all the hives were still stacked with honey.

Perhaps both queens were too weak to withstand the exceptional wet and humid weather we have had for the last two months. For April we normally have 20 mm of rain. This April we have already had 100mm and the forecast is not looking better for the week ahead. With continuous rain, one of the hives showed signs of water penetration. This would weaken them at this vulnerable time of the year. This hive had no visible brood left on the panels. I suspect the queen had been dead for some time as there were no visible signs of any brood been laid. There were, however, heavy signs of dysentery at the top of the brood box.

The other hive did have some small brood patches left with pupa. They were at around the 16-18 day when they died. This would mean the queen started to lay in February, as normal but died not long after. The odd drone was found on some panels also. Not too sure why they would still be in the hive at this time of year. If anyone has any info on this matter, we would appreciate it.

winter clean01

My conclusion:   varroa destructor mite

All signs point to the mite being the reason for the hive losses. We have large hives with big bee populations, therefore, it becomes more difficult to eradicate this pest. 

In the coming weeks, we will check again on the two remaining hives. An extra feeding will be given and the hives arranged to prepare for the coming year. Hopefully with bees…

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