a mystery, absconding?

[peterdbk]

I've been coaching a high school girl with her beekeeping. Today she wrote the following to me:
"Last weekend I checked the living hive and they had started to produce brood, I was feeding them syrup, they seemed to be taking it well.They were bringing in fresh pollen and I saw them busy at the cherry tree that was blooming at the front of my house. Today it was strangely quiet, no bees. I opened up the hive all the bees were gone. There were a few bees, dead ones clinging to the frames. The whole upper deep hive body was full of capped honey, the frames that had brood were completely empty. It is so upsetting, why did they leave? I loved those little guys."

This is in southern New Hampshire. She told me the brood she saw last weekend was eggs and young larvae. The cluster last weekend spanned 3 frames and was between the size of a softball and soccer ball. The cluster was in the lower deep and the brood was on a dark comb. She said the upper deep, which was full of honey, was dark comb. The small number of dead bees she saw were scattered around in the hive, particularly in the top deep, as though they got caught by declining temperatures while foraging inside the hive sometime during the winter. The hive is entirely BeeMax EPS. She feeds syrup with a top feeder that is made form EPS. She saw no dead queen. The queen came from me and was produced from a swarm cell or supersedure cell in the summer of 2010 (or there was a supersedure in her hive last summer). The hive was gentle and performed well last year. She measured mite levels last September by counting daily mite drop and we concluded that she did not need to apply any treatment.

What happened?

[Allen Dick]

Tough to say without being there. One glance might tell the tale whereas remote assessments often as not miss the mark, but we'll try.

FWIW, this is not what is normally meant by absconding. In an abscond, as I understand it, most or all bees simply leave with the queen and move elsewhere. This looks like a dwindle.

1. Clusters that small far down in the hive in spring have a hard time maintaining heat and are vulnerable to chills if they commit to brood. By spring they need to be up against the lid where they can conserve heat and an insulated lid will allow a doubling of cluster volume. I wrote about that in the diary yesterday. (At least, I tried to, but need to refine the concepts into simpler terms).

2. It seems curious that only open brood was observed.

3. What was the daily mite count? Do you recall, or can you recall what your threshold was? The date in September is important, too.

Drops and washes in September are notoriously deceptive. As days pass, mite counts balloon as brood area contracts through September into October and November and mites are forced out of their hiding place. Up to 90% of the mites can be in brood in August/September. (I only became aware of that recently and always wondered how the mite counts could escalate as much as they do). Some hives produce brood longer than others and the mites remain concealed longer and that can hide a serious infestation since thresholds are based on averages and such hives are outliers.

This is my pet peeve about most bee "science" which concentrates on means and ignores the outliers, or discounts them. The 'exceptions' in a yard of one are very significant. In larger yards, variations from the norm are a huge management problem for a beekeeper, yet the averages conceal the probable difficulties. My recent drop chronicles demonstrate how the individuals making up an average may not be represented well at all, but the composite chart looks great.

[peterdbk]

> small clusters and heat loss
I agree with you on the concept and arrange all my hives accordingly.

> It seems curious that only open brood was observed.
That brood was started at the time natural pollen may have became available at her location. My observation is that Russians are broodless for much more of the winter than any other bee I have used. The hive is 100% EPS which may have reduced foraging on chilly days. The thermal mass of all that honey up top would tend to keep the hive interior cool.

What I find especially interesting about the brood is that she saw it on the weekend and it was all gone by Friday. So it died and was cleaned out, or the bees ate it, or her traditionally good observation skills are not accurate in this instance.

It is possible that this hive is protein-constrained so that it starts brood when pollen comes in and then has to abort it if there are a few days without pollen. This could explain the lack of capped brood last weekend. I need to get her to tell me how much stored pollen is in the former cluster area. Last spring she gave this hive patties and this spring she has not AFAIK.

> mite levels
I gave her 1% mites to bees as the threshold and some parameters for estimating that ratio based on hive measurements. I did not check her calculations. She has a sharp eye and did not observe any DWV last year.

> Dwindling vs absconding
I have a lot of personal experience with dwindling and tiny colonies (baseball and smaller size). I have never seen a colony like this one dwindle that fast. If it did dwindle, and the old bees made it out the door to die, then the queen should still be there (plus a few dozen bees) in the cluster area or below. This girl has not found her.

[Allen Dick]

I think we are trying to read things into an incomplete report. Without certainty on some of the facts, nothing can be concluded.

In my experience, whenever some event seems to be novel, further investigation almost always shows the explanation to be one of the top three or four causes of bee death alone or in combination.

Entia non sunt multiplicanda praeter necessitatem

[peterdbk]

She went through the hive carefully today and sent me some photos. She noticed spotting on frames and hive walls, so we now have confirmation the bees were sick. The fact she has not found the queen's corpse could be explained by the queen having died a few months ago (which would imply the girl's brood sighting last weekend was mistaken).

[Allen Dick]

That makes more sense. Pictures really help.

Sad, though. I can understand the disappointment. Hope she does not feel it was her fault. Sounds as if she did everything right.

Sometimes s*it happens.