Mould on Comb

Hi, I have just inspected my Warre Hive (16/02/2013), located in Yatton, North Somerset by briefly opening the side windows to view inside. I noticed a green mould growing on the comb and parts of the comb have broken/split. The bees are still flying, although there aren’t many. No bees could be seen inside through the windows. My query is whether the mould on the comb is a problem and is it an indicator of a general poor health of the colony?

Thanks for any feedback.


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3 Responses to Mould on Comb

  1. simplebees says:

    Hi Andrew

    It suggests that the bees are not able to fully maintain the internal atmosphere/conditions of the hive. This can happen with colonies that are on the weak side. One of my Warrés has mould on the pollen on the end comb of the box in which the bees are over-wintering. This comb is mainly full of capped honey with the odd cell of pollen. The later cells have developed a rather attractive fur of bluey green (Penicillium??). A few weeks ago I thought this hive had perished as it showed no activity even when the other hives were flying in mild weather. But more recently, with the occasional warm sunny spells we have had, this hive too is flying, although not as strongly as the others. Moreover the bees are now beginning to move over the face of the comb with mould and are cleaning it up, albeit slowly.

    In general, my view is that the mould one sees in such cases is not harmful and my experience is that the bees clean it up when the weather allows. Yes, weak colonies tend to show mould growth more than strong ones, but this does not indicate disease per se, just lower numbers of bees in the winter cluster.

    Excessive mould, particularly where combs turn black or pink over the whole surface, suggests damp getting into the hive from outside or pockets of stagnant damp air in the hive. I have seen this a lot with horizontal hives in the winter/spring (one reason why I moved back to vertical ones) but have not seen it so far with Warrés.

    During cold weather, comb becomes very brittle and such comb can easily fracture – one reason not to disturb or move hives in very cold weather. The broken comb you are seeing reflects this. Has the hive been knocked or moved?

    Gareth, Cotswolds

  2. johnmkubwa says:

    Andrew, I agree with Gareth. Small winter clusters maintain the essential nest warmth but this may not reach the corners of hive boxes. I have seen moldy corners in Warré hives – especially last year when there was much damp weather over summer.
    The lack of activity may indicate a shortage of stores. How heavy is the hive? What is your estimate of food reserves. I do give small colonies, in their first year and short of stores in early spring, a kg of fondant as a top feed but some prefer to leave alone and allow natural selection. In March you should be able to ‘rate’ your colonies by activity and pollen intake, see also Warré page 86 ‘Beekeeping for All’. I no longer support weak colonies beyond a small feed; they can consume much time and often fail anyway if the genes are poor.
    I inspect (to confirm no disease) and cull or unite colonies. This reduces risks of robbing and may give you a small harvest. It also frees up a hive for a new swarm (but remove any black old brood combs) Regards
    JohnH, Hampshire

    • andrewprz says:

      Gareth/John. Thanks for the replies. Capped cells holding honey can be seen from the viewing window and their number/distribution has changed little over the winter to date, suggesting that food reserves remain. I’ve not lifted the hive to gauge its weight, but will do this. I think having a second hive might be of benefit to help compare colonies during the winter period.
      Andrew, N Somerset

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