All the colonies survived into March but Clarissa did not last into April. Since that happy day of observing traffic from all the hives, we had been uncertain of seeing any from her. Confusingly we would see foragers come to the entrance, flit about a bit, and then suddenly dart off to enter Beatrix or Dorcas. A very few may have entered but we were unsure. The other hives definitely had traffic.
Three Sundays ago we were sitting on our bench, watching bees at work, and finally lost patience. Without suiting up we impulsively opened Clarissa and had not a single bee come to question our intentions. Grabbing a hive tool, we somberly poked through the combs. She resembled a typical winter varroa death as described in this article. [Edit: 2021-Apr-23 Changed to link to a newer version of the article per comment from its author.] Looking at its points in detail:
- The colony was big and looked healthy in the fall.
Yes, it did.
- A lot of honey is left in the top supers.
Equivalently for our horizontal hive, the combs furthest from the winter entrance are full of honey while those nearest have just bit at the corners with slightly moldy cappings.
- The cluster is now small, maybe the size of a softball.
Smaller. And moldy.
There are hardly any bees on the bottom board.Definitely dead bees on the floor. Not as thick a carpet as we have seen but more than “hardly any”.
- Near or just below the cluster is a patch of spotty brood – some fully capped, and some with bees dying on emergence (heads facing out, tongues sticking out).
Nearly no brood at all. We did see one cell where the occupant had just cracked open the capping and expired.
- If you look closely in the cells around the brood, you will see white crystals stuck to the cell walls, looking like someone sprinkled coarse salt in the brood nest.
In past years before we took varroa monitoring and treating seriously, we would see such small crystals in many cells. We thought they were sugar until we learned that they were guanine from varroa waste. We see some such cells this time and more with large blobs. Incontinent varroa on diuretics? Could they possibly be larvae that had gone through a few freeze thaw cycles? We have not read of such a thing but the color and volume of these deposits do not quite match varroa poop descriptions or our previous experience.
- You don’t have records showing that varroa was under control.
And there is a bit of a puzzle. We do have records indicating that varroa was under control except in Dorcas, not Clarrisa. We applied the oxalic treatment to all the hives anyway and verified that the mite count in Dorcas had declined to our target level. It is true that we did not check Clarissa’s mite count post-treatment but it had already been fine pre-treatment.
So Clarissa may not tick all the boxes for winter varroa death but it still seems the likeliest explanation at this point. And our fault yet again.
2021 April 22 at 15:42
So sorry to hear this 😦 Was she in a long horizontal hive? I think those can be harder for the bees to keep warm in colder climates.
2021 April 22 at 15:49
Thank you for the sympathy.
She was in a horizontal hive as were/are two colonies that survived. The claim that horizontal hives are less suitable for cold climates is oft repeated but we have not seen any side-by-side study to support it.
2021 April 22 at 15:54
I haven’t seen any other studies either to be honest, but just wonder as in nature research suggests swarms usually prefer a 40 litre volume cavity. That is about the size of the National brood box we use in the UK; I don’t know how that compares with yours?
Could be something completely different that caused her loss of course. Our poor bees face so many pests and pressures in their environment nowadays.
2021 April 22 at 17:11
National hive bodies are, we think, roughly comparable to Langstroth, so picture two-and-half of your boxes pushed together.
You can check our MBA talk for exact dimensions and other information. 8)
2021 April 23 at 01:07
I have actually updated the article / talk to remove number 4 – I’ve seen plenty of bees on the bottom board now. I think it depends on how early the viruses hit – if it is warm enough for the bees to fly (fall), the bees will leave, but if it is when it is cold, they can stay on the bottom board.
2021 April 23 at 10:12
Thank you for the update. We tried to edit to link to the newer article at your website, The Sand Hill, but wordpress seems to have made a local copy. We shall have to stay vigilant for further updates.
2021 April 23 at 07:48
Oh, that’s sad. 😦
I don’t know why you say that it’s your fault, though, except as interferers in the lives of bees, as beekeepers….
2021 April 23 at 08:44
We fell down on our caretaking duties of animals in our care.
2021 April 24 at 13:16
So sorry for this. I’ve been reading more about mite drift into hives late into the Fall, so even though you treat the bees rob out a failing colony and bring back mites as well as honey. Glad to hear the others are doing well.
2021 April 24 at 14:39
Thanks. We think that is why Dorcas’s count spiked so suddenly. We treated all the hives because we feared Dorcas would infect them as she died. But she survived (so far) and the treatment(s) failed to protect Clarissa.