Further details on the colony losses mentioned in the March newsletter
Michael Main writes:

I have heard of at least two members who have experienced the same problem as me this year (see March newsletter).

I went into Winter with 4 strong colonies (brood on 6-8 frames) and 4 weaker ones (brood on 3-4 frames) last inspection 21st September.  The strong colonies had stores of 35 – 40 lbs and the weaker ones 25 – 30 lbs.  Bees were flying well and bringing in pollen and nectar from the last of local Himalayan Balsam and Ivy right up to early November.  I have kept an eye on stores through Jan and Feb and checked the hives for Woodpecker damage and hive condition regularly. Although seeing no sign of activity I did not worry as it was cold and wet the bees should be in a cluster keeping warm. 

On 6th March, as it was warm and the bees were flying from one hive, I lifted the roof from one of the other strong hives.  There seemed to be no activity and the crown board was cold so I lifted the corner and peeked under.  Still no sign of life so removed the crown board and looked down between the frames.  To my horror there seemed to be no bees in the hive as there was a clear view of the mesh floor between each frame.  I repeated this on all 7 hives with no activity and the situation was the same. 

I then re-opened the strong hive and inspected the frames. It had started the winter on double brood and the top box was still almost full.  It also had plenty of honey and pollen in the bottom box around the brood area but all the brood area frames had empty cells where the brood had hatched.  There was one small group of dead bees covering about one square inch but no other bees except a few dead ones, as I would expect, on the mesh floor – less than a cupful in total.  The same appeared on all these hives.

All boxes were shut and sealed to avoid robbing. They have now, on advice from the Bee Inspector, been dismantled, combs rendered down and frames and hives cleaned and sterilised.

My only explanation is that the queens had failed during the autumn or succumbed to a viral infection. They were all 2019 queens but some were quite late in mating. Although the bees had been working the late flowers the colony was rapidly being depleted of bees, dying on the wing. During winter, those remaining continued cleaning the hive on warm days leaving very few in the hive at the end. All colonies have had the remaining bees tested for Nosema* but all proved negative. However, if my explanation above is correct, the remaining bees were the younger bees, they were not mature flying bees that should be used for a Nosema check so that conclusion may not be correct.

I have now closed up and sealed all entrances to avoid robbing.  Before I dismantle and clean the hives what steps should I take to find out what has happened to the bees?  Take samples and photographs of the frames?  I know the seasonal bee inspectors are not operating yet.  Can I get an inspection as soon as they start again and if so should I defer the cleaning process until then? Photos of one of Michael’s negative Nosema slides this year and, for comparison, one of his positive samples from last year, are at the end of the Newsletter, p12.

Michael Main

I am sure that Michael would welcome any suggestions as to what may have caused the remarkable loss of his colonies. Please copy such suggestions to the Editor for the benefit of the readers.

Thank you Michael for sharing this detailed account with the rest of the members. Unlike this one, reports of this kind of experience sometimes do not contain sufficient detail for the recipient to draw many conclusions.
I am sure that we are all very saddened to hear of this event in your apiary, and hope that the explanation will be found, and that you find some good replacement bees.

If you have, or another beekeeper you know has had an experience of high losses similar to Michael’s, please let me know and I will put these reports into the next Newsletter, with or without your name, as you wish. This information could be very helpful as an indicator of the scale of the problem, which seems to be unusually bad this year.

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