Winter Survival

Murray McGregor shows a winter cluster
Murray McGregor shows a winter cluster

How this Walrus does it

I harvested my last honey in August and treated for mites as soon as the honey supers were off. This works for me. Many beekeepers leave the harvest until later, maximising their honey crop, but I’m happy with what I do. At that time my bees are still bringing in nectar from Himalayan balsam, but my priority is always to ensure that varroa mites are knocked down before the queen starts to lay her “winter bees”. I treat them again in late November, with oxalic acid this time, to take advantage of lack of brood in the hives in winter.

The flow from the balsam into September was good news because the bees stored it above and around the brood nest, to be eaten later on in winter and spring. Generally, my production colonies do not need to be fed enormous quantities of sugar syrup in the autumn, but sometimes the odd one does. 

Horses for Courses

Some beekeepers rely on a late honey crop, for example, heather, so they have a different way of doing things to me. In fact, for the two UK based bee farmers in my book (Murray McGregor and Peter Little), heather honey is a big deal. They don’t bring hives down from the hills until after the heather crop is in, which means that they are feeding bees into October and sometimes November. Each beekeeper has to develop his or her own system, one which works for their location, climate and beekeeping priorities.

Peter Little, hive in winter
Peter Little, hive in winter

People who are new to beekeeping are naturally distressed when they find that some of their colonies died over winter, and they often conclude that the death of their bees had something to do with the winter weather. Clearly, weather plays a massive part in the fate of our bees, but it isn’t necessarily the winter weather that’s the problem. I asked Michael Palmer (Vermont) about this last week:

Mike Palmer says…

Walrus: Hi Mike. When you had that polar vortex thing in the States, with very rapid temperature drops to deep cold, did you notice higher bee mortality? 

Mike: No, I didn’t notice higher mortality.

Walrus: Do your winter losses show any correlation to bad winters? I suspect not, but good to check! I think maybe poor summers lead to weak colonies over winter; a strong well fed colony would survive almost any winter…thoughts?

Mike: Yes, exactly. Summer/autumn weather greatly affects winter survivability. Last year (2018) was a good example. We had a good flow until the first week of July. Then we had a hot, dry August and September. Drought! Then October was cold and wet, followed by two “one-foot” snowstorms in November. It was very cold in December and January.

  Clusters of older bees were going into winter because the lack of flow in August and September stopped the queens laying. Then spring came late. The first pollen came on 20 April. The nucs couldn’t take it – most were too weak to sell. The production colonies recovered this year to make a good crop. This year is much better: 450 nucs going into winter well-stocked with young bees and honey.

I have heard similar stories time and again from bee farmers. They know about keeping their bees healthy and well-fed and free of mites, but they can’t do much about the weather. It’s not so much the winter weather as the weather before and after. If the summer is miserable, then colonies will go into winter weaker than they should. If the following spring is cold and wet then already weakened bees can succumb.

Murray McGregor’s worst year

Here’s what Murray McGregor in Scotland said about his worst year:

We had a disastrous year; 1985 was a terrible summer. A terrible summer actually hits you with a double whammy, because there was very little blossom honey, then it rained all through the heather. It rained almost every day from the end of June to the end of October. There was flooding, no heather honey and the bees stopped raising young bees, which was what made it so very serious. We had very little honey, and what happened with so few young bees is that we had a huge spate of winter losses. The hives that survived winter and were alive in early 1986 were undersized and took much of the year to recover. So, 1986 was just as bad a honey year as 1985 but was caused by a combination of it being another poor summer and the lack of bees early on. It took two to three years to recover from 1985.”

We cannot do anything about the weather, but what can we do to ensure that our winter losses are low? Here are a few things that might swing the odds in your favour:

What do bees need?

A strong colony of healthy bees, including many young bees laid in the autumn (so-called winter bees). Prof David Evans recently posted about a study which showed a strong correlation between colony weight and winter survival. Weak hives are more likely to suffer from isolation starvation. That’s when the cluster of bees cools down to the point where they are unable to move to nearby honey stores. Healthy colonies have low mite counts and show no signs of disease.

Adequate stores of honey and/or sugar syrup. Bees are experts at regulating the microclimate inside their hive and in their winter cluster. They need fuel to generate heat, and that fuel is honey (or syrup). They also need water, particularly the bees in the centre of the cluster, but that’s quite a complicated process which I will write about another time. Most of the stored honey will be consumed in late winter and spring, as the amount of brood increases, because brood requires tightly controlled temperature (34 – 35 Deg C) and humidity. Bees also break their cluster during warmer spells in winter which can be a problem.

Randy Oliver says, “in my experience, the least efficient wintering occurs at around 55-60˚F (13-16˚C), when it’s not quite warm enough to forage, yet not quite cold enough to form a tight cluster, but warm enough to establish a brood nest. Much energy is wasted as the colony breaks cluster each day in preparation for possible (and often fruitless) foraging.” He’s in California; my bees will forage at 13 Deg C, but that’s not ideal in the middle of winter when flowers are not about. 

A young, well-mated queen. Sometimes queens that were mated late in the season, or when the weather was poor, will become drone layers because of a lack of sperm in their spermatheca. Older queens who have been furiously laying for two or more summers may also develop the same condition as their stored sperm runs low. 

A weather-proof cosy home to live in. They should not have too much empty space; just enough for the bees and the honey. Polystyrene hives are better insulated than wood, but there are pros and cons to both. In my wood hives, I make sure that I have inserted insulating material into the roof, which reduces some heat loss and hopefully prevents condensation forming above the cluster of bees. 

Stream Time!

Anyway, having blasted through my allotted 1,000 words, I’ll call it a day. Time to watch some House (Amazon Prime), or Punisher (Netflix) or Dickinson (Apple TV+).

3 thoughts on “Winter Survival

  1. Rick Barnett

    Always makes me smile reading your fascinating blog

  2. Hello Walrus

    I suspect quite a bit of “isolation starvation” is actually due to disease in the colony. A large cluster should be in closer contact with the food stores and is better able to thermoregulate the cluster. In contrast, a cluster with higher levels of DWV dwindles rapidly over the winter as the actually-short-lived-but-should-be-long-lived winter bees perish. Consequently thermoregulation gets problematic, they need more stores per bee to keep warm and the shrinking cluster gets further and further away from the stores.

    What should be done is compare the virus levels in colonies that perish from ‘isolation starvation’ with those that die out for obviously non-disease reasons e.g. queen failure, or – of course – a healthy colony.

    I’ve briefly covered this in “Survival of the fattest” ( but should perhaps expand on it a bit more. Healthy winter bees can live for months (at least 9 month under experimental conditions).


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