Autopsy report

[Bakersdozen]

I am posting this so that others may learn.  I will start by saying this has been a challenging year for me.  Beekeeping took a back seat to the demands of life. I will not beat myself up over this.  You do what you have to do. I played catch up with hive inspections and mite treatments.  I will admit, if I had the time, I would have done hive inspections and mite treatments in a more timely manner. 
In the past few days we had a couple of afternoons the bees were able to fly so I took the opportunity to check on food stores and colony general welfare (aka are they alive?).  I had put emergency sugar bricks in each colony, around Thanksgiving, for peace of mind.  All colonies had been treated for mites and went into winter with counts under control.  At the time I put sugar bricks in I noticed drones inside one of the hives.  Drones?  In November?
I found that colony dead this week.  It appeared the colony died during the recent subzero cold snap.  As I disassembled the wooden ware, I did an "autopsy".  As I disassembled I recalled that this colony was slow to build up in the spring.  When the queen started laying, it was mid nectar flow.  She continued to lay very late into fall.  This was based on observance of orientation flights.
This first thing I noticed was a large number of dead bees, with some drones, on the bottom board. So, it was a large cluster. They were all over to one side of the bottom board.  Did they cluster over to one side and eat all the food around them there fore starving?  I kept disassembling.  Frame by frame I took the hive apart.  No bees with their head buried in the comb.  So, they didn't starve.  I found plenty of food stores.  There were a dozen or more queen cups all through the 20 brood frames.  Also, there was a wee bit of drone brood.   I concluded that the colony experienced queen failure in the fall, tried to requeen but was unable to.  A laying worker took over the queen's job and that is why I saw drones and orientation flights when the queen should have slowed down or completely stopped laying.

Another thought comes to mind too.  When the colony was experiencing slow build up in the spring, they might have been rearing a new queen that was poorly mated due to the extended rainy weather we experienced.  The new queen fizzled out quickly and the colony was unable to rear another queen from existing eggs, if there were any.  This is just speculation. After all it's easy to look back and see the puzzle pieces come together.  Sometimes it's hard to interpret what you are seeing when it is actually happens.
Any thoughts?

[Wandering Man]

Wow! So much information in this one post.

I’m sorry for your loss, but thank you for posting this very useful autopsy.

[brooksbeefarm]

I have seen this many times and almost always when you see a lot of drones being carried over winter the hive was queenless, or the queen was a weak one and did not produce a large enough winter cluster. If i can catch it in time i will kill the weak queen and combine. Sorry for your lose B13, i hate cleaning up a deadout hive. Jack

[Jen]

Baker... Exact same scenario's here in upper northern Calif. We just discussed this at our bee meeting this week. We are getting dead outs early in the winter, and we haven't even had a cold snap yet.

Slow to build up in the spring
Queens laying late into the Fall
A few bees dead on the bottom board, no queen found amongst the dead
Plenty of food/stores/sugar
A smathering of dried up capped cells

We also had a very precarious spring, I had a heck of a time keeping queens alive from queen cells while making nucs. Then there are two queen breeders in our area, the queens that were purchased have either died, or the bees balled them, or just plugged along until the hive died this winter. It's been frustrating to say the least. I too purchased 3 queens this last spring and all three of them perished. I believe that those queens may not have had enough pheromone right from the beginning.

We all surmised that there wasn't ample warm days in a row for the queens to get fully bred.

[Bakersdozen]

I have seen this many times and almost always when you see a lot of drones being carried over winter the hive was queenless, or the queen was a weak one and did not produce a large enough winter cluster. If i can catch it in time i will kill the weak queen and combine. Sorry for your lose B13, i hate cleaning up a deadout hive. Jack

I am kicking myself in the rear.  I caught an August swarm that I housed in a nuc box.  The idea was to have a spare queen just in case I needed her.  I did need her, I just didn't realize it.  By the way, the very small swarm and queen are doing just fine in the nuc box.  I have kept sugar bricks and fondant on them because they don't have any stores.  I am sure they have eaten through the extra frames of honey I put in there.

[Riverrat]

Do you have to top of the hives cracked open a bit to ventilate the hive?  Sounds like you might have had condensation drip from top of hive down onto the cluster causing them to die out in the cold

[Bakersdozen]

Do you have to top of the hives cracked open a bit to ventilate the hive?  Sounds like you might have had condensation drip from top of hive down onto the cluster causing them to die out in the cold

Yes, and shims with entrances.

[Lburou]

B13, I found a dead hive this past week.  It too had been just hanging on all summer.  I should have combined it in the fall, but I decided to let them fend for themselves over winter.  There are just a few hundred dead bees on the frames and bottom board.  It is hard to see the dead queen in the middle of those bees because she shrivels up and doesn't look much different from a worker unless you can get lucky and see the back side of her thorax.  I am posting an article (with permission) about losing hives over winter that may add something to the discussion here:

Why did my honey bees die?

Learning to identify a common cause of winter death

Meghan Milbrath, Michigan State University Extension, March 3, 2016

Beekeepers have already lost a lot of colonies this winter. While official counts won’t be recorded for a few months, some trends are starting to emerge. One of these trends is a specific type of colony death. I’ve received so many calls describing the scenario below, that I can describe the deadout before opening the hive, or before the beekeeper describes it over the phone. While I may impress some with these predictive powers, the frequency of these types of losses indicates a real epidemic that is affecting honey bee colonies in northern states.
Characteristics of the common early winter death in northern states:


The colony was big and looked healthy in the fall
A lot of honey is left in the top supers
The cluster is now small, maybe the size of a softball
There are hardly any bees on the bottom board
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).
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.
AND

You don’t have records showing that varroa was under control.

Sound familiar?

We see this classic set of symptoms over and over in the states with a proper winter. A big colony that seems to just shrink down and disappear. Many people want to use the term colony collapse for this type of death, and while collapse is a good descriptor of what happens, this is not true colony collapse disorder. This is death by varroa associated viruses.

How does it happen?


The big colonies –While beekeepers are often surprised that their big colonies are the ones that are gone first, it makes perfect sense in terms of varroa growth. Since varroa mites reproduce in capped brood, the colonies that made the most brood (i.e. got the biggest) are the ones most at risk of having a high population of varroa. Colonies that swarmed, or didn’t take off, or even fought a disease like chalk brood are less at risk from high varroa populations, because they didn’t consistently have large amounts You should have good notes indicating cluster size going into winter, but even if you don’t, you can see the large circle of food eaten by a large cluster.


This colony had a large brood nest (indicated by the dark comb in this frame from the top deep box), and a large cluster going into winter (indicated by the large amount of honey that is eaten away where the winter cluster started). Varroa were never monitored or managed in this colony, and it was dead by February, if not sooner.


Lots of Honey – Lots of honey means that the colony died fairly early. Colonies with high levels of varroa, they tend to die fairly early in the season (before February), leaving lots of honey behind. Once the bees are stressed and in cluster, the viruses take their toll very quickly.  In some cases the colony will even abscond in fall, or be dead before winter really hits.
The colony shown above had a third deep box that was filled with capped honey, indicating that the bees died early, and starvation was not the culprit.


Small cluster – Varroa levels peak right when the winter bees are getting formed. The bees that emerge from varroa infested cells are weakened, and more importantly, are riddled with viruses. Varroa mites are notorious for carrying deformed wing viruses (DWV), but are known to transmit many more. When bees are close tight in a winter cluster, the viruses can spread very quickly.
In our colony, the cluster was only the size of our hand – some bees had their heads stuck in the cells, trying to stay warm, others had fallen between the frames.


No bees on the bottom board – When a colony starves, the bees just drop to the bottom board, and you end up with a pile of dead bees in the hive. When bees get sick with viruses and other pathogens, however, they often will fly away. Sick bees by nature leave the colony to die in the field, an act designed to prevent pathogen transmission in the colony. When most bees are sick, they either fly away, or are too weak to return after cleansing flights. An early fall illness means that a lot of the bodies probably got removed by workers too.
The colony we examined had only a few bees left on the bottom board (1-2 cups). We didn’t see a lot of varroa, but there had been some robbing, so wax cappings covered a lot of the board.


Patch of spotty brood/ Bees dying on emergence – When a colony succumbs to varroa associated viruses or parasitic mite syndrome (PMS), we see a lot of effects in the brood. Unlike American Foulbrood (AFB), which attacks the larvae at one particular stage, PMS will affect developing bees at many stages of development. It is one of the only diseases where you see bees dying right as they emerge.


Note the bee in the upper left is fully formed, and died on emergence. You can often see frozen/melted larvae along with dead pupae. Many beekeepers instantly suspect AFB, but AFB infected colonies usually will not be large and have produced a lot of honey going into the winter.


White crystals in the brood – Around the cells where the brood died (the last place of the brood nest), you will often see white crystals stuck to the walls of the cells. These are dry (not suspended in liquid like crystalized honey), and are the crystallized pee of varroa. Varroa mites defecate in the cells, and the resulting guanine crystals are left behind, and visible to the naked eye.


Cells on the right hand side of this photo contain small crystals of guanine acid, indicating varroa defecation. Notice the dry, irregular shape, and that they appear stuck to the walls on the cells. Some cells on the left hand side of this photo contain crystallized sugar. Note the wet/liquid appearance, and that it is largely in the bottom of the cell.


No records that varroa was under control. Notice that this says ‘varroa was under control’, and not that ‘the colony was treated’. You may have applied a treatment, but it may have been too little, or (more likely) too late. This year was a particularly difficult year for this, because in Michigan we had a really late summer – it stayed warm enough for beekeepers to go into their hives well into October. Many beekeepers took the extra time to put on a varroa treatment, thinking that they were lucky to get one in. While that treatment could help the bees for next season, it was too late for this winter. September and October treatments would have been applied after varroa had gotten to their winter bees. Winter bees are born in the fall, and with their special fat deposits that allow them to live through the winter months, they are the one who carry the colony to the next season. If the winter bees have already been infected with viruses, the damage is done. No amount of treatment or varroa drop would bring the colony back.

The only way to know that you have varroa under control is to monitor using a sugar roll or an alcohol wash. Just looking at the bees does not work; varroa mites are so sneaky, that you rarely ever see them, unless the infestation is out of control, and it is too late. Many beekeepers say that they never see varroa in their hives, so they don’t think that they have a problem. In fact, a varroa infested hive can actually look like it is thriving. Underneath the lovely brood cappings, and away from our view, the mites are reproducing and biting the developing bees. The colony can look fairly healthy until the mites reach a threshold, and the colony succumbs to disease. By the time you see parasitic mite syndrome, or see varroa crawling on bees, it is often too late for that colony (especially if winter is just around the corner). Getting on a schedule of monitoring and managing mites will give you peace of mind that your healthy looking colony is indeed healthy.

The silver lining

If the above scenario is familiar, don’t despair. First, you are not alone. Many beekeepers got caught off guard with varroa this year. They didn’t realize how bad it was, or got thrown off by odd weather patterns. Second, when the bees die, the varroa mites die too. We don’t yet have evidence that the viruses would stay in the equipment, so you can reuse your old frames. The honey that is left can be extracted to enjoy (if you didn’t feed or medicate), and frames of drawn comb can be given to new colonies. Most importantly, if you recognize the above scenario in your colonies, you now have more knowledge as to what is harming your bees, and you can take positive action. You have time for this season to develop a strategy. Monitor your varroa mite levels using a sugar roll kit (available at pollinators.msu.edu/mite-check/ or at Mann Lake), read about integrated pest management for varroa, and make a commitment to prevent high mite levels this year before your winter bees are developing. This is going to be the year!


Meghan Milbrath, Ph.D.
mpi@msu.edu /517-884-9518

This article is used with permission, and was first published by michiganbees.org.

CLICK HERE to see the article above as it was published at the Bee Informed Partnership (with the pictures).

[Jen]

Lee..    You are our encyclopedia of information and reading material. Soo Appreciate You!  This is a fab article and I forgot about the little crystals left on the walls of the cells. Good reminder!

[Lburou]

.

[Bakersdozen]

Thanks for posting the article, Lee.  That is excellent information.  Several indicators of parasitic mite syndrome could apply in my circumstance.  With a drone laying worker, and varroa's preference for drone cells over worker cells, it is possible that the varroa population rebounded after treatments. 
As the article indicates, large food stores will be present.  That was true in this case.  But, I had a large pile of dead bees on the bottom board.  Certainly enough to form a good cluster.  There were also dead bees scattered about on the frames.  The drone brood died in the cells, not on emergence.  I concluded the drone brood died from being exposed to cold temps after the nurse bees died.

[Les]

The entries by Baker and Lee are why this forum is great. Information is shared to help us bee better beekerpers (or at least try LOL).

[neillsayers]

Thanks B12 and Lee,

Good info

[SmokeyBee]

Wow, that article describes my dead out exactly...

[efmesch]

A great reference, Lee.  Could you possibly provide a link to the original article so we can see the pictures referred to.

As a small contribution to the article, I would add a recommendation that beekeepers make a practice of opening drone cells to check them for the presence of developing or adult varroa.  Varroa mites have a preference for laying in drone cells because of the larger sized larvae which gives them a better supply of food on which to develop.  You needn't open them all and eliminate your supply of drones during the spring and summer, but checking them before an upcoming winter, when the drones are not needed anyway, you can easily get a picture of the presence of a potentially deadly infestation.

[neillsayers]

A great reference, Lee.  Could you possibly provide a link to the original article so we can see the pictures referred to.

As a small contribution to the article, I would add a recommendation that beekeepers make a practice of opening drone cells to check them for the presence of developing or adult varroa.  Varroa mites have a preference for laying in drone cells because of the larger sized larvae which gives them a better supply of food on which to develop.  You needn't open them all and eliminate your supply of drones during the spring and summer, but checking them before an upcoming winter, when the drones are not needed anyway, you can easily get a picture of the presence of a potentially deadly infestation.

Ef,
The link is embedded under the word here at the end of the post. I copied it for future reference.

[Bakersdozen]

.

As a small contribution to the article, I would add a recommendation that beekeepers make a practice of opening drone cells to check them for the presence of developing or adult varroa.  Varroa mites have a preference for laying in drone cells because of the larger sized larvae which gives them a better supply of food on which to develop.  You needn't open them all and eliminate your supply of drones during the spring and summer, but checking them before an upcoming winter, when the drones are not needed anyway, you can easily get a picture of the presence of a potentially deadly infestation.

In my circumstance, this would have been excellent advice.  Had weather and my available time permitted, this would have given me an idea about the varroa levels rebounding.  Sacrificing a few drone brood, any time of the year, is cheap insurance to know if you have a varroa problem in the imminent future.

[efmesch]

Thanks Neill---I guess I have to learn to pay more careful attention to all the little "hints" left behiind.   

[Lburou]

Thanks Neill---I guess I have to learn to pay more careful attention to all the little "hints" left behiind.   

Don't worry, you are 'Entitled' on this forum.  ;-)

I changed the link a bit to be less obscure.  HTH

[Bakersdozen]

As I stated at the beginning of this thread, I hope others will learn from my experience.  Here is the next chapter of this story. 
I saved all the frames, for later use, (albeit one that was broken) from my lost colony because of the drawn comb and honey stored by the bees. 
Last August, when I didn't get a swarm trap down, I caught a very small swarm.  An experienced beekeeper would have killed the queen and combined with another colony.  I didn't.  I kept them, fed them, and put in a nuc.  My thoughts were to have a queen available should I need one.  I did, for the lost colony, but time and health kept me from realizing it.
The little swarm is alive and well.  I sneaked a peak yesterday.  So, Wednesday, when the weather is supposed to warm to 60 degrees, I am going to move the little swarm into double 10 frame boxes with frames of honey from the lost colony. The queen should start ramping up her laying and the colony will have plenty of food.  They only have 3 frames of comb at present.
I feel confident about using those frames because the colony died when they lost the queen at a bad time, not disease.