Winter Loss – What happened to my bees?

If you are reading this the chances are you have lost your bees over winter, you are feeling upset and saddened and you want to know why they have died and most beekeepers think “What did I do wrong?”

There are always winter losses and there are many reasons why colonies don’t make it through winter. It stands to reason that the more colonies of honeybees you have the more likely you are to suffer with winter losses and it may not be anything you have done so before you go blaming yourself see if you can see why the colony has died. It may be that you can’t work out what has happened, below I have given some examples of winter losses.

Starvation – there are two types of starvation, one is beekeeper error, you took too much honey off your bees and didn’t bother to check them through the winter and they have starved. The bees will be found with the heads in the cells because they are desperate for food. This is your fault entirely and yes you should blame yourself, this was completely avoidable and its because you were greedy – sorry but that is exactly what this is. The early spring is often when we see this, the bees become active, the beekeeper sees the bees flying and assumes they are collecting nectar. Well have a look around you, how much flower is there and is it warm enough for the nectar to flow. Yes they are bringing in pollen, but they need nectar and now they are active and the queen is laying they need more and more of it. They will be eating more than they can forage and so they starve.

The other starvation is “Isolation Starvation“. This happens when the winter cluster of bees moves away from food instead of with it. The result is the same, dead bees with heads in cells but you will also have frames of food in the brood box and even more sadder is that the food may only be a couple of inches away from the dead cluster. This is not your fault, do not blame yourself, there is nothing at all that you could have done to help these bees. Sadly nature has a weird way of working at times.

Queen issue – If your colony was queen-less going into winter they are not going to survive, even if there are still some alive in early spring they are not going to live long enough to support the colony until you can get a new mated queen to go in with them. If you are lucky enough to find mated queen early the bees will be too old to support her. It could be that you had a late supercedure happen and she didn’t manage to mate. A colony with a drone layer is not going to make it, again this may make it through winter but, sad as it is, the colony is doomed.

Varroa / Unhealthy colony – An unhealthy or stressed colony is unlikely to make it through winter. Varroa causes much stress on a honeybee colony, to avoid high varroa levels going into winter make sure you treat your bees at the end of the season. I have a post on Varroa which will give you much more information on this topic. Make sure you look at the brood throughout the season to see that it looks healthy. Also look at your bees, do they look healthy? Varroa damage can be seen at larvae stage and also at capped stage, your bees will detect infected cells, they will uncap them and remove the infected larvae, so look for chewed cell capping’s. You could take some blame for this if you didn’t treat your bees.

Unusual winter with temperature changes – With climate change we are seeing winters with more and more temperature fluctuations. The bees cluster in winter during the cold weather, if we have warm days they will break this cluster and maybe even go out to forage in the warmth of the sun. The winter days are short and the temperatures drop quickly, this can have a big affect on the bees, some won’t make it home because they get too cold and in the hive they may not make it back to the main cluster and they may die from the cold. A small weak colony will almost certainly die in a big hive as they won’t be able to generate enough heat. You definitely can’t blame yourself for this, no one can control the weather!

Predators – Mice are big winter predators to honeybees, the bees offer a lovely snug warm environment with lots food for them! If they get into the broodbox they will cause lots of stress to your bees. By fitting a mice guard or simply reducing the hive entrance to a single bee space you can stop mice getting into the brood chamber.

Moisture – moisture by way of condensation can cause detrimental effects at any time but especially during the cold winter months. Make sure your hives have appropriate ventilation, many beekeepers make the mistake of covering both holes in the crownboard, this stops the airflow and causes condensation. This may cause the demise of your colony. If you think your bees have died due to excess moisture have a look at the hive ventilation and also look at the location of the hive, does it very wet/damp where the hive is located?

Blocked entrance – Your bees need to be able to get out of the hive, even in winter they will take short cleansing flights if the sun is out. If the entrance is blocked by something they won’t be able to get out. It could be heavy snow fall causing the blockage or it could be early spring, there will have been natural bee deaths over the winter months and if the colony was big going in these numbers will also be big and could block a small entrance.

Beginner’s FAQ: What Should I Do During a Hive Inspection?

There are a number of things you need to keep in mind when doing a hive inspection. This can appear a little overwhelming at first, but once you are inspecting your hives regularly this becomes second nature. Each of these elements on the list are equally important as if there is anything out of sorts with even one, then your hive will become less productive and healthy.


It is essential to ensure that your hive is what we refer to as ‘Queenright’ meaning that your colony has a normally laying queen. At certain times of the year your queen may go off lay and you won’t see any eggs. This would usually happen during periods of dearth when no nectar is flowing, or as the weather gets colder. Most times when we inspect a colony it is not essential to physically see your queen, if we have eggs this will usually be enough to confirm our colony is queen right. Once a honeybee egg is laid it stays in this stage for 3 days, therefore if you see eggs then you can be assured that your queen was present a minimum of 3 days ago. 

Always check for the presence of queen cells too, these could be swarm cells which may be related to the ‘space’ element within your colony, or they could be supersedure cells. (See our separate post about what to do if you have queen cells).

So how can you tell if your colony is not queen right? Well, of course if there is no presence of eggs… But its not always quite that simple! Workers are also capable of laying eggs, but they are unfertilized, meaning they will only produce drones, you may also have a queen that has turned into a drone layer, this is a mated queen that has run out of her sperm stores.

The topic of identifying queenlessness in your colony is far too extensive to discuss here but we will soon be going into that in another post!

Can you see the Queen?


No matter how frequent your checks are, you should be looking at what stores your colony has.  Do they have enough stores to sustain them until you visit them again? Take a look at the young larvae, do they have a good amount of royal jelly in the cells, or are they looking dry?  If your colony is struggling for food the larvae may look dry.

When checking your colony for stores you do of course need to think about which point in the season you are in. Is there a strong nectar flow on? Is there going to be poor weather? Is there a lot of brood in the colony and therefore more mouths to feed? These are all questions you need to ask yourself to ensure that you can estimate if they have enough stores. Also remember that the stores don’t just refer to the honey, but also to the pollen present in the colony. Without adequate stores of the pollen the nurse bees will not be able to produce food for the growing brood. You may find that in a queenless colony your bees do not gather pollen, for this reason we always stop for a moment and watch the returning foragers as this gives us good idea if our colony is queen right with brood.

So how much stores should you need for a full-sized colony? This question is not quite so simple, and the answer will depend on where we are in the beekeeping season.  As a rule of thumb, you may say that your colony should never have less than the equivalent of two full brood frames of stores in your colony. However, if we are in June or July and have big colonies 2 frames of stores with no new stores coming in is clearly not going to be enough for your bees. We would hope that in June/July we have a nectar flow on and our hives have supers on that the bees are packing nectar into so there will definitely not be food shortage problem. However, there is usually a break in the nectar flow during the season, this is called “The June Gap” (which is not always in June, it can be a lot earlier).  Usually when the June gap hits, your colonies are nice and strong and therefore depending on how long the gap is your bees can eat their way through those supers full of honey very quickly! If this happens the amount of stores may be an issue, it is not unheard of for bees to die of starvation mid season due to a dearth in nectar flowing.

More stores are obviously needed to get your bees through the winter months, so the rule of the equivalent of 2 full brood frames of stores when we are in late September is also not going to be enough.  Check out our post about winter preparations for your bees. 

Commercial brood frame, note the stores at the top of the frame

Disease & Pests

The topic of disease and pests is so vast that it needs an entire blog post dedicated to it as well. We will just briefly discuss the importance of detecting disease early on.

During your hive inspection it is important to inspect larvae carefully, they should be well formed (clearly see their segmentation) and pearly white. Anything out of the ordinary is worth having a closer look at. Check all frames and see if you have similar larvae that is causing concern elsewhere in the colony. If you do see something that does not look right take good clear photos and show a fellow experienced beekeeper.  If you want to revisit the same frame later use a queen marker or even your hive tool to mark the top bar of the frame so you can locate the frame again. There are some relatively common brood diseases that show now and then like chalk brood, sac brood, stone brood and bald brood. These are usually not much of a concern and you do not need to notify anyone. If however you do have larvae that looks like EFB (European Foul Brood) or AFB (American Foul Brood) you need to get in touch with your local bee inspector as these are notifiable diseases; contact details can be found on BeeBase.

How does the pattern of your sealed brood look? Is it a good and consistent pattern or is it pepper-pot-ish? If the pattern is pepper-pot, by this we mean that the pattern has empty cells. This can be a sign of high brood mortality, the bees will have uncapped and removed any dead larvae thus leaving empty cells, or it could be diploid drones which do not survive to full development and again the bees will remove them leaving a poor laying pattern. A pepper-pot pattern can also be a result of a queen who is having difficulty laying.

Also have a look at the floor, are there a lot of dead bees that the colony are struggling to clear away or are there lots of dead bees outside in front of the hive? It is worth mentioning that you will most likely always see dead bees outside the hive after winter. Depending on how strong the colony is you may also find that you have lots of dead bees on the hive floor. A stronger hive will have plenty of workers who will keep a clean house and they may have removed them but a colony that is struggling will not have the man power to house clean.  If however you are mid season and you see lots of dead bees there may be a problem.  Also look at the adult bees, do they look healthy overall? Are their wings deformed or do your bees look hairless and shiny? 

In the case of varroa infestation, any damage can be averted as long as you treat before your mite levels are growing beyond your colony’s control.  If you do see signs of varroa damage in the colony treat straight away.  All colonies will have varroa however some bees will be better at tolerating / dealing with varroa then others.  You can manage your varroa by proactively doing a mite count.  We have a separate FAQ’s page covering varroa. 

Shiny hairless bees may be chronic bee paralysis virus (CBPV). If you’re not well versed in the various diseases and pest damage, I would seek help and advice from an experienced beekeeper. You can also find lots of advice on BeeBase.


Whenever you are doing a hive inspection you should always be considering the available space for the bees. From the moment you take your crown board off you should be able to see if there is a suitable amount of space in either the brood box, or if you have supers on, space in the supers. As a rule of thumb, when you supers are full of bees, that means all frames covered in bees, you are ready for a new super.  If you don’t have supers on your bees yet, then see how many frames your bees are covering in the brood box. If they are really congested, you may have seen evidence that they have started to build wax up through the holes in the crown board and into the roof!  Be wary if they have done this as they may be so congested that they are pulling queen cells with a view to swarming – see our separate post on swarming! 

It’s not only about giving the bees enough space to expand, it is also imperative to not be giving the bees too much space before they are ready. A smaller colony may not have enough strength in numbers to keep a constant temperature throughout the hive and as a result they may struggle to stop any brood from chilling. 

On the other end of the spectrum, as mentioned above the lack of space pushes the bees to start thinking about swarming! All beekeepers want to avoid their colony from swarming because it takes a lot longer for a colony to become productive again.  There is also the risk that the new virgin queen may not come back from their mating flight. Rule of thumb is that 1 frame of capped brood will become 3 frames of bees so as you’re going through your hive consider whether you may need to add supers.  It seems obvious but do consider the time of the year, don’t be adding supers too late in the season as your colony will be reducing not expanding.

In Summary

I hope that gives you a good idea of the four main elements to keep in your mind when going through a colony. It may seem that there is a lot to remember, but as your experinece builds up these will become second nature and in time things that don’t quite look right will stick out like a sore thumb.

When first starting out it is always best to have a good mentor who can assist you when you’re going through your colonies, they may be able to spot things that you miss. Before you know it, you’ll probably become a mentor to a beginner beekeeper yourself!

Rob was initially my mentor before becoming my business partner!