CSI: colony postmortem
Here’s an exercise for all you hive detectives out there. Beekeeper Aaron Althouse from here in the Pacific Northwest recently lost one of his two hives. He performed a postmortem, took many photos, and wrote an analysis, all of which is posted below. Your task is to see if you agree with his conclusions or have another idea altogether.
I have my own opinion but I will wait to see what you think. This is a good opportunity, especially for new beekeepers, so see what a dead-out hive might look like. It is also a chance to see how a thorough colony postmortem is done.
Nice job, Aaron. Thanks for sharing!
Colony Postmortem by Aaron Althouse
Olympic Peninsula, Washington
One of my two colonies recently died out. I don’t recall exactly the last time I saw bees flying from the opening, but I’m pretty sure it was about 3 to 4 weeks ago, since I know I checked them after the cold snap we had about mid-December.
Last Wednesday (January 14) we had a brief respite from the rain and wind, and the sun poked its head out for an afternoon. I walked up to my apiary and looked at what was happening, and saw no activity in that hive, while the other hive a had small number of bees flying and moving about its opening. Expecting the worst, I went ahead and took the lid off and lifted up my moisture quilt box. I saw a number of dead bees on top of the frames, many of which seem to be in mid stride. Since I didn’t have a lot of time, I put the quilt box and the lid back on and waited for a dry day to do a more thorough investigation.
- The wood shavings in the quilt box were dry as a bone. I did not see any sign of infestation or anything else that makes me think that some other creatures had moved into the hive.
- Looking down into my top deep, I saw what I refer to above, a number of bees on and in between the frames that look normal, except that they are not moving.
- I removed the (very heavy) top deep and inspected the bottom deep. I see a little bit of bridge comb as expected, and not much else. There are again a few bees here and there that look normal, but none are moving. I do see some evidence of mold, but that is likely not the cause of the dead out.
I broke down the hive and put in my wheelbarrow and wheeled it down to my garage where I could take a closer look without being rained on.
The manner in which I loaded my wheelbarrow meant that I started inspecting the bottom deep 1st.
- The outer frames have what I am pretty sure is pollen; some of it is starting to mold. It seems a bit wet. The frames are only partially drawn out.
- As I move to the next set of frames, I’m finding more wet pollen, this time with more mold, and good amounts of capped honey. I don’t think I see any brood yet, which is expected since this was the bottom deep.
- Getting into the 3rd or 4th frame, I see a number of uncapped honey cells, which are bubbling. My assumption is that this is “wet” honey that has gone to fermentation. At this point, I also see some cells filled with white goop that I think may have been brood.
- The capped honey is generally found on the section of the frame that would be away from the side of the hive facing the sun. I do not see the classic pattern of brood, pollen, and honey arc.
- I removed the rest of the frames and pulled the hive body off of the bottom board. I see what I think is about 1000 dead bees that are now mostly moldy. If I combine them into one group, they would probably cover about one third of the screened bottom board, one layer deep.
- The top deep feels like it is loaded with honey. It is heavy and awkward to move.
- The 1st 2 frames I pulled are filled with capped honey. There are a few bees on the frames, none are inside the cells.
- The 3rd frame shows a bit of cross-comb but nothing dramatic. There is plenty of capped honey and a number of empty cells. There is more of what I think is old brood.
- Between the 4th and 5th frames I see what I am pretty sure is the remnants of the cluster. It is about the size of a racquetball; way too small to be effective. It is on the sun-facing side of the deep body. There are bees in the cells and appear to be surrounding something. I’m pretty sure that if I dissect it I will find the queen. That particular frame has almost no brood or pollen, but does have capped honey on the far side. There does appear to be some capped brood right next to the cluster.
- On the next frame, I find lots of wet pollen, capped honey, and more of what I think is old, capped brood. I am not sure, because it is tan in color and the capped honey is white, but when I scratch off the capping, it seems hard as if it was animal fat or lard. I did not use grease patties.
- The 6th or 7th frame shows only one old supersedure cell, that does not have deep cells in it, so it may just be some burr comb.
- The remaining outer frames are filled with normal, capped honey.
- My initial thought was that the bees starved. Upon finding bees in and around capped honey, I can’t say that this is a very good likelihood.
- There was no significant moisture in the hive; it was dry except for some of the uncapped nectar that drained out as I was moving frames around. The bees do not show signs of infestation, Nosema/dysentery or foul brood:
- They are not greasy or black.
- They do not have separated wings or K-shaped wings.
- They did not die with their heads in the cells; the weather was previously cold.
- There no dead bees seen outside the hive.
- There was no discernible smell other than the sweet smell of honey. There was a distinct lack of what I could determine as likely to be brood, capped or uncapped.
- There are no brown or yellow stains all over the outside of the hive. It’s true that these could have been washed away by rain, but I have never seen anything like it and I walked by them on a regular basis.
- Given the cluster size, I have to assume that during a break in the weather, the bees broke cluster and were caught in a sudden cold snap and were not able to regroup and generate enough heat to stay alive.
- One other possibility is that the queen died unbeknownst to me and did not lay any brood, so the majority of bees died of old age and the remaining few that were there clustered around themselves in a feeble attempt to stay warm.
Click on any photo to see slides.
Editor’s Note: My own theory will be in the next post: “Last thoughts on a lost colony.”