Post-Mortem Examination

What's on this page?

The post-mortem is an excellent skill for any beekeeper to develop, treatment-free or not.  Knowing what killed your hive is the best way to understand how to prevent it or what to do about it in the future.  In my case, Iím not doing it to figure out how to treat in the future, Iím doing it to understand how a portion of the bees is doing overall.  If I can put together the signs the hive is giving before it dies, then I can know which hives not to breed from or which ones which can be redeemed by requeening before they fail.  Let us begin.

So letís go through an imaginary hive and see what we can see.  There are a lot of things to look for and to see.  We can start by looking at the exterior. 

What does the entrance look like?  Is there bee poop around?  Is there a lot of bee poop around? 
If there is some poop, it may be nothing or it may be a sign of dysentery.  If there is a lot of poop, smeared around, it is probably a sign of dysentery or related disease.  A robbed out hive will often have pieces of wax cappings littering the entrance and some small smears of propolis.

Are there dead bees?  Are they clogging the entrance? 
A dead hive will often have bees littering the bottom as there is no one to haul them out.

Is there water dripping out of anywhere?  Are/were there any icicles hanging from the upper entrance if there is one?
If so, check into condensation as a possible problem.

Are there wads of mooshed up bees lying around the base of the stand?  Is the grass and dirt torn up?  Are there scratches at the entrance?
If any of these are present, look into skunks.  The hive will also be largely if not completely depopulated.

Is the lid or other parts leaky or rotten?
Perhaps equipment failure is to blame.

Now letís look inside. 

As you take off the lid, is there a smell? 
Check for rotten bees, wetness, fermented honey.  Fermented honey can be a sign of honey that was not cured and capped to begin with, especially important if you fed syrup.

What do you see on the top bars?  Is there condensation?  Is there mold? 

Mold is a sign of too much water in a hive.  Streaks on the comb are a big sign of dysentery.

Is there bee poop? 
Dysentery or related condition.  Also possible that the bees never got an opportunity for cleansing flights.

Is there honey left?  Where is the honey?  Are the bees surrounded by honey? 
If there is no honey left and everything else checks out, it's pretty obviously starvation.  Dead cluster on brood 6" from honey can be starvation because of the brooding.

In what condition is the comb?  What is reusable and what is not?
If you can reuse this equipment, do.  Do not reuse comb with signs of American Foulbrood.

Has the hive been robbed out? 
Robbing can identify the time period of the death.  Remember what days bees were flying throughout the winter to pin it down.

Is there brood? 
Could be starvtion due to the bees not being able to move off the broodnest.

Looking through the frames, where is the cluster?  Does it look like the brood was abandoned?  Is there more than one cluster?  How big is the cluster? 
Small and divided clusters can be due to disease or mites.  Sometimes bees not well adapted to their climate can starve within inches of honey even without covering brood.  They don't have the ability to move in extreme temperatures.

Is the queen present in the cluster? 
Hard to find, not a huge indicator if you can't find her.  If you can find her then you can eliminate queen loss.

Are there queen cells? 
Perhaps a failed late season supersedure or queen loss.

Bottom Board
Now the bottom board, there is always information on the bottom board. 

How many bees are on the bottom board?  Is it generally clean or is it totally covered in funk?  Is there a puddle?
Indicators of the rate of bee death and timing.  Rotted goop is a sign of water.  A puddle is a sign of the hive being tilted to the back rather than forward which can lead to significant queen loss.

Are there mites?  How many? 
There will probably be a few mites if you look hard enough.  Massive amounts of mites are pretty obvious.

Are there small hive beetles?  How many? 
Small hive beetles will overwinter in the cluster.  I have found dead hives with more than usual, but it's the larvae that cause the damage in hives.

What does the entrance look like?
There could be signs of dysentery.  Signs of robbing include a general muddy appearance which is a mixture of wax, propolis, and honey as the robbers have made a mess and tracked some of it out the front door.

These are questions you can ask to help you discover what went wrong.  One of the first things you should figure out is if it was your fault.  If the hive starved out and they had enough stores going into winter, than it is an issue of bees not being frugal with their stores.  If the starved out after you harvested honey when you shouldnít have, then you bear responsibility.  But donít get too down on yourself, learn from your mistakes and move on.  For what good is a mistake if nothing is learned from it? 

Further interpreting the signs can be difficult.  Iíve seen virtually everything blamed on mites.  Iím not saying that mites arenít playing a part, but not everything is the mitesí fault.  I have had bees brought from warmer climates have trouble wintering.  I have had bees in the spring being severely predated by skunks.  Look for the signs and learn from them.  If you are going to buy bees, buy them from north of you, and if you have skunks, use upper entrances or an electric fence.

Case Study: 1

Here is a hive that died in the fall of 2011, some time around Thanksgiving.  Here was the lower cluster.
Deadout, Lower Cluster

And here was the upper cluster.
Deadout, Lower Cluster

As you can see, the queen was found in the upper cluster.  The hive was composed of three deep boxes and included an upper entrance and a closed off lower entrance.  The white stuff is granulated sugar which fell down from the top where it was being fed in the fall.  There was open honey stores all around.  The hive had several frames of pollen.  There were half a dozen small hive beetles on the bottom board, and about two dozen mites.  This hive was a swarm that was caught the previous year and was productive and frugal at that time.  It had been superseded at least once in 2011 and there were leftover queen cells in the hive.  There are more details in a post dedicated to this hive on the blog.

Case Study: 2

This is a hive that died sometime in January or so at my north yard in Greenland Arkansas.
Dead Cluster

Opening this hive revealed a small cluster but more than enough honey.  The cluster was over several frames despite its small size.  As you can tell, the above frame is plastic while the lower one is foundationless and drone size comb.  This hive probably did some sort of freezing to death when we had temperatures down to -5F.  This was a swarm caught in the summer of 2012 in NE Fayetteville.  I judged it at the time to be from a kept hive rather than truly feral.

Case Study: 3

This is another hive from my Greenland yard, died about the same time as 2.
Dead Cluster

Here is an example though not a great example of a divided cluster.  Plenty of honey still in the hive.  Notice how the cluster is above some of the honey, clusters do not generally move back over empty comb.  This is especially important in trough or topbar hives where the cluster may end up in one end starving while the other end is full of honey.  There is also a small patch of capped brood here.  Final prognosis is probably that of a too-small cluster getting a cold snap.

Case Study: 4

Another hive, same location and date.
Dead Cluster

Look at that excellent small cell comb on the right, definitely going to reuse that.  I'll reuse the other one as well, you can see the light brown of the comb telling you that it is young, probably two years.  Decent sized cluster, though you'd think with that proximity to honey they wouldn't have starved, but you can also see the capped brood on the upper right.

Case Study: 5

Another in the same location and time.
Dead Cluster

This one turned out to be the only one in this location that well and truly starved.  There was virtually no honey in this hive.  The cluster is small and the mold shows it was probably dead before the other ones died and has been dead since late fall or early winter.  Also, no sign of robbing (jaggedly torn honey cappings, sticky wax and propolis tracked out the entrance and entrance littered with cappings.)  I'd probably say, any hive worth being called a survivor should survive long enough to rob the deadouts and still survive the winter.  The comb on the left is getting a little darker, starting to build some drone, but still only 3-4 years old.

Case Study: 6

Fifth of six hives from Greenland yard.  The sixth was the only one alive after the date these pictures were taken, February 17, 2014.
Dead Cluster

Though you can't see it on this frame, this hive had plenty of honey, including a half full medium which sat on top of this box.  Not much to see here, year-old comb, sitting on honey and pollen, doesn't look like brood was an issue, this was the mother of one batch of queens from last year, a good performer, left behind plenty of honey and good comb.  These temperatures (-5) were the lowest I've seen since I've lived here which is nearly 7 years.  This is not the first time there has been a substantial dieoff at a serious low temperature event.  Christmas of 2009 yielded 0F and a loss of 5 hives.

Bottom Board

Here's a picture of the bottom board.  You can see a lot of dead bees, a little mold, even some drips of water or diluted honey.  A quick check did not yield any mites, though maybe you can spot some.  This is a good color for a bottom board, most everything is light colored.  You don't want black or dark with lots of moisture and rot.

Case Study: 7

Coming (hopefully not soon).