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Discoloured frames and degrading plastic

The frames in my super are discoloured. It looks like mould. When I try to clean it with an ear bud, the colour does not come off. I have also noticed in both the dark section and the clean section the plastic has become soft; sort of chalky. When I place my fingernail in the plastic it breaks down easily; just as if it were bees wax.

The frame in the photo is the outer frame and has no honey. The inner frames are full of honey except where the frame is darker. The bees seem to be avoiding the darker cells.

Note that my flow hive is about 18 months old so should still be in good shape.

Any ideas as to what the problem would be and any suggestions for solving this please?

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Hi there. Are you sure it is not beeswax your fingernails are digging in?

Did you leave them in the sun?

I think you need to take apart and clean them, and get in touch with Flow. Please let us know the outcome.


Hi @KeithB these do look very dark. The best way to clean them is with very warm water (but not hot). Don’t be overly concerned if the blades come apart (or if you need to separate them to clean properly) as they can be put back together. It’s a bit of a fiddly and annoying task but quite doable. Please let us know if you need any further assistance at all. The ones with honey are likely fine to leave as is for now and clean up next time they’re empty. Does everything look okay in your brood box? It looks a bit like smoke from here… is that a possibility? Or could be mould. Is there any smell to it? What is the climate like where you are?

Definitely mould. Left your super on over winter?
I have some the same, the bees will wax over the mould and not clean it first so warm water and or bleach will not clean it off.
Either break them apart and clean or do what I did and leave it, it didn’t affect my harvest last summer.
It may even be beneficial. :grin:


Hi @Freebee2. The ones with honey only have a small strip at the end which the bees are avoiding. The brood box is fine. It’s been a warm winter here in Queensland. Temperatures between 6 degrees c and mid-twenties. So quite warm as winters go.

@skeggley, thanks for the tip. I think I’ll take it apart and clean it. Big job but probably worth it as the bees seem to be avoiding the dark spots.

You may have a point @Honeyeater, maybe it’s wax on top of the cells. I can’t detect any smell.

Tomorrow I’ll take apart and clean. I’ll let you know the results.

Thanks for all the assistance!


I left my super on over winter and had some condensation issues. I don’t have any mould at all though.

I have a quilt box in top, and open screened bottom. I got temps as low as 4 degrees this year and the bees appear to be happy in both hives. Whether they prefer a different setup, is another story yet to be written.

It has been a very mild but a wet winter here, I would go with your idea of cleaning the frames with @Freebee2 's ideas. Any frames I have had with mold on them my bees avoid totally so danged if that is a benefit to bees when they leave any area on a frame with mold on it.
It has been a great Winter for the bees with a good Winter flow of honey around the coast. If it continues we can expect a good Spring. I’m already doing Spring splits and Jeff is busy making up nucs so keep and eye out for signs of swarming out there.
Cheers Keith


@KeithB I look forward to hearing how you go - please reach out to us if any further assistance is needed. Cheers


Hi @Peter48. Good to hear from you. Good to know you’ve had a similar experience with mould avoidance.

In the last 12 months I got only one harvest. Hoping to get this spring off to a good start as the hives are reasonably full already. How did you go?

I will be keeping an eye out for swarming behaviour. Maybe time do do my first split?

I’m already doing my Spring splits as a way to prevent swarming. I prefer to do them before there is queen cells but I’m finding some have already made them. So I’m busy kicking my back side about that.
With the drought for over a year it was a hard time till the rain eventually came in the end of February and finally there was nectar in the flowers in the bush. Since then it has been great and I have had an extraction of my wooden hives and the poly hives are doing even better, the poly hives are killing the wooden hives for honey extracted by at least 20%. I’m doing some extracting over our Winter as hives are becoming honey bound. The drought has had an effect even down on the coast but nothing compared to others. The drought really made life tough for bee keeping.
When you decide to do a split and being your first time I am happy to guide you thru it if you want a hand doing It can be a bit nerve racking when you do your first, and that is ok to be a little uncertain on how to do it as best for the bees. Your close by so no problem to give you the time mate.
Cheers Keith

I thought Skeggley might be onto something there so I researched the topic a bit more.

Apparently, a common mould in beehives is Penicillium waksmanii which is indeed beneficial because it is an antibiotic, and may also help ward off AFB and other bacteria.

How good is that?


Think I would rather keep my hive as dry as possible and forego the mold. It is hard to change after 48 years of being told differently, but each to their own ideas and experience.

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Hi mate, my comment was sort of tongue in cheek however in wild colonys there is lots of detritus in the bottom of the cavity and there are log hive beeks who swear by it. (GregV :wink:) the bees propolise it however beneath grows moulds and other insects like pseudo scorpions and wax moth which are thought to perhaps have a symbiotic relationship with the bees which could explain why wild colonys in cavitys can prosper when keepers of bees in the same area struggle with varroa, SHB and all the other nasties in their hives.
Of course we find the solid bottom boards in a healthy colony to be meticulously cleaned but screened bb’s are different scenario again.
As I stated earlier I have flow frames which are mouldy and the bees have not ignored them and have filled them with honey. Perhaps this may not be the case in brood boxes although once the comb has coloured with cocoons would you even see the mould?
Food for thought. I’ll see if I can find some links when I get a chance.

Minds are like parachutes, they only work if they are open.


Apparently, a common mould in beehives is Penicillium waksmanii which is indeed beneficial because it is an antibiotic, and may also help ward off AFB and other bacteria.

Wow that’s interesting, I didn’t know this. Bees never cease to amaze me.

I have this exact mold in my flow frames from leaving them on the hive over winter. there is ZERO point leaving them on where I am- after 6 years I now am certain of this. I have had limited success cleaning the frames by soaking them in warm water with some napisan (a cleaning product for nappies!). Then I rinse them a lot and blast them with a high pressure hose. It does not remove all the black but a good deal. I wish I knew of some safe cleaning agent that could strip frames?

As others have said- the bees will still use the frames when they are darkened like that. But I would prefer to keep them looking cleaner if i could.


I have just been reading a great bee book called ‘The Honey Factory’ and it says that bees have no ability to measure humidity in a hive. It is speculated that this is because in a bees natural home there is practically never any condensation that forms on the inner surfaces. the bees are able to perfectly regulate conditions and so have never had to evolve a capacity to assess humidity levels. I also read in another book that bees can cope with cold way better than they cope with dampness. This makes a lot of sense to me- bees can survive in Australia with hives completely exposed just hanging off a branch in a tree. Of course they would need to eat more honey to keep the brood warm but they can do that.

For these reasons i agree that I would much rather keep my hives dry. here in adelaide we see quite a lot of condesntion in hives over winter. Oftentimes this year i have lifted off the lid to find it completely wet underneath. I mitigate this issue by ising hive mats to stop the water dripping down over the brood frames- but there is still mold all over. That is why I plan to experiment with quilt boxes and/or insulated lids.

so far my quilt boxes seem to be working well: I use a layer of wood chips about 2 inches deep. The top of this layer is soaking wet when I open the lid- but when I dig down the bottom layer is completely dry and warm. The one issue I will have to keep an eye on is propolis- it may be that the bees end up propolising the mesh and thereby make the quilt boxes non-functional. However I don’t think they will do this here in Adelaide- as I have found our bees produce far less propolis than bees in NSW where I have recently been working with an urban beekeeper in Sydney. I would estimate Sydney bees produce 5 times more proplis than Adelaide bees do. I have no idea why- perhaps they find it more easily or maybe they need it more in those conditions. On average Sydney bees are about 5 times less aggressive too! Bees in Adelaide tend to be darker brown- and feisty- whilst the bees in Sydney are the lighter yellow type and very relaxed in my experience.

Fun fact: Propolis comes from the greek- pro meaning before and polis meaning city. Bees traditionally ‘proplolise’ around the entrance to their hive so we call it propolis- as it is placed ‘before the city’.


I totally agree that bee can’t regulate humidity which is an issue in human made bee hives and not in nature. Humidity in a hive when condensation occurs isn’t good for the bees - period.
I cured my condensation by fitting roof vents into the roof at each end to improve air circulation up there.
I’m not have propolis as an issue here. Just the amount you would expect where the bees need it.
Cheers Jack

This discussion has evolved to be very interesting! There’s so much to learn.

My cleaning efforts have been to no avail. However, I’m heartened to learn that the bees will still use the frames in their discoloured state. I did leave the frames in the sun for a few days in an attempt to kill any mould. I’m not sure if this will help but did it anyway.

I am definitely going to take the advice of @Peter48 to place vents in the roof of the hive. I should have listened the first time he recommended this approach (I must be a slow learner). Hopefully this will help to alleviate condensation, especially in colder months. I’m intrigued by the idea to quilt the roof too. I assume this helps insulate the roof which we, as humans, like to do in our own homes.

Thank you all for your contribution to this discussion.


The best way to stop condensation in the super is to remove it in the colder months.
My bees told me they don’t want their warm air leaving through top vents in winter by propolizing them up. I certainly wouldn’t want holes in my ceiling letting warm air out during winter either insulation however, yes.

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I left my super on over my first winter, but I had 5 frames full of honey. The girls have helped themselves to a fair bit of it. Yet to open for a thorough inspection. Can visually see some mould, but not to the extent seen above. Might try a quilt box next winter.

I also found honey in the chambers that had fermented. I unblocked the feed back hole and the bees started lapping it up… will they get drunk? Will they redeposit that honey? Will it affect the honey I extract at a later date?