Beekeeping notes by Amanda Millar
After such a promising and hopeful start in April, May has turned out to be something of a disaster in my apiary.
On 28th April I had the first signs of Chronic Bee Paralysis Virus (CBPV) in my largest, best colony, and subsequently two thirds of my colonies are showing symptoms although these are abating thankfully. Research by NBU has found this virus to have increased greatly in recent years and over half of colonies contain the virus, whether or not they show symptoms. Since 2016 it has hit between one and 4 of my ~ dozen colonies a year, starting between early April and end of June but most have outgrown it after about 3-4 weeks, or less if only a mild attack, once better weather returns. A couple of colonies I culled in the early years. This year is definitely the worst – I wonder if many other beekeepers have it? It usually affects the largest most successful colonies after a spell of cold or wet weather confines them indoors, enabling the virus to spread. Symptoms include, black shiny, hairless, trembling bees, some with K-wing, outside the entrance and on the top bars. Hundreds of dead bees outside; the numbers can be confused when shrews, slugs and other animals dismember and eat the fresh ones over night. Clustering at the entrance and up the sides of the hive is obvious and activity is less purposeful. If bad, the floor may be covered with dead and the entrance blocked and you may find dead drones and workers in the frame runners and the colony population will be depleted. There is little which can be done except sweep up and dispose of the dead bees outside otherwise they will smell and only spread the virus via slugs and small mammals (it helps if a large slab is in front of the entrance otherwise they will be lost in the grass and it may not even be obvious that you have a problem). Remove any dead from the runners and check the mesh floor regularly, remove the entrance block. I have looked at which colonies have been affected over the last six years and have seen no recurring pattern. If there had been one colony, which regularly gets it and seems to be genetically vulnerable, I would cull them.
CBPV clustering up front and dead outside
Prevention is supposed to include giving them plenty of space (as required but not overdoing it which can also cause stress and chilling if the weather turns cold), and above all being hygienic with equipment, hive tool etc. Readers will know I am scrupulously hygienic (I dare say some would say obsessively so); I clean tools and gloves between colonies and don’t swap frames or boxes. I also believe I am timely with the space I give them and do not stimulate them to unnatural expansion early in the year by feeding – they just do what they want, although the lack of queen excluder certainly enables expansion of strong colonies. It is possible I have too many colonies for the area, or too close together. I suppose the only silver lining will be that these colonies are not thinking about swarming as their population is on the decline, so inspections need not be so frequent although I shall need to check they have not lost their queen, which may happen. I found those affected to be very docile (or demoralised). The honey crop is sure to be adversely affected. The Beelistener blog had a very pertinent article on stresses and disease in bees last month, which is worth reading; I wonder if there is anything I can improve on. https://www.beelistener.co.uk/bee-health/honey-bee-health-welfare-dr-chris-palgrave-comments/
CBPV dead/dying bees
June can still be a busy month to monitor for swarming and with any nectar gap will be over early in the month if not already (the horse chestnut was over by ~22nd May). The main nectar flow of blackberry will soon start as I noticed the first flowers on 24th May. In 2019 the first blackberry flowers were open on 30th May, and it was all over by mid July (I did not record last year), so be ready with supers if not already on. It’s the ideal time to get foundation drawn.
Alliums are very popular with bees
Queen rearing. Although May is normally the most likely month for queen rearing, April was rather cool and unsettled and part of May, so it is likely some colonies will be thinking about swarming in June too and you can indulge in a bit of queen rearing, hopefully with better queen mating weather. Rather than repeat at length what others have said more succinctly I urge you to read the May blog article by Professor Evans at https://www.theapiarist.org/timing-is-everything/
He also includes a handy crib diagram of timings of development and queen mating etc, which of course we should all know by heart but is a handy reminder if you find yourself in a panic with unexpected queen cells and brain fog strikes!
I was delighted to see he recommended and had just carried out the same procedure I did in late April before CBPV struck (allow for temperature differences between Sussex and Scotland!) to easily requeen a swarmy/grumpy colony when you find queen cells, by removing the queen and a week later removing all the queen cells allowing suitable time (read the article) for them to be hopelessly queenless. Then introduce a frame of suitably aged larvae from your best colony for them to produce new queen cells, which you can then harvest. My procedure went well up to the point when I went to harvest 2 of the 3 sealed queen cells I knew were in there; only to find them all torn down and killed with holes in the sides of the cells and contents. So no spare queen to requeen my nuc, which I had discovered had just become a drone laying queen.
When I had removed all the queen cells from this swarmy colony 8 days before, I had discovered one which looked suspiciously as though it had emerged, but when I found new queen cells made on the frame from my chosen colony I hoped all would be well. This virgin must have taken a week to get to the top of the stack of boxes to find the ‘nice’ queen cells and kill them. As they had no brood I gave them a frame from a good, healthy colony just in case she did not mate, to prevent drone laying workers developing and they now have sealed queen cells so that swarmy virgin was lost. Actually most of the colony was lost to CBPV and from 5 boxes, I have removed 3 as they are now down to about 7 seams. No more seem to be dying (well there aren’t many left!) so if they recover and get a queen mated all well and good, otherwise there is not much more to lose there and the swarm half of the artificial swarm, next to them, is doing well.
So back to my drone laying queen in a nuc; I found and squished her and cut out all the distorted drone brood patches from the 5 frames of brood they had and gave them a frame which perfectly had only eggs and sealed brood. When I looked recently a queen had just emerged. They will have had a brood gap of 7-10, but already the colony size was a couple of seams smaller than when last I looked. Fingers crossed for some really good weather soon for so many reasons.
Research – Clever bees, https://theconversation.com/honeybees-join-humans-as-the-only-known-animals-that-can-tell-the-difference-between-odd-and-even-numbers-181040