What to do with moldy combs

A few years ago a beekeeper friend announced to me that mold had taken over her hives and killed all her bees. Now whenever I see mold—or even hear about it—I think about her. When I tried to explain that it was the other way around, that the bees died and then the mold came, she didn’t believe a word of it. She cut out all the combs and washed the frames with bleach. Too bad.

A variety of molds will grow on the combs when the moisture in the hive gets too high. The moisture gets too high when there are not enough bees to fan it away. I suppose the confusion arises because these moldy combs frequently contain dead bees that are also covered with mold, so it looks like the mold killed everything.

According to various sources, one of the molds frequently found on combs is Penicillium waksmanii which can actually inhibit the growth of certain bacteria, including American foulbrood. Other molds are usually present as well, as evidenced by the different colors—usually blue, white, yellow, or gray.

If you have a dead hive loaded with mold you will be tempted to discard the comb, but it is usually not necessary. The first thing you need to do is decide how the colony died or became weak. If you can eliminate American foulbrood and colony collapse disorder, then you can re-use the combs.

The first thing to do is take the frames to a warmish, dry place where they can dry out for a few days. These things can smell wicked—like moldy stuff does—so put them in a place where they won’t bother you. Separate any frames that are molded together and let them air dry. As they dry the mold growth will slow down and then stop.

Once the combs are dry you can store them in an empty super. After your colonies build up in the spring you can place the moldy super on top of a big, vigorous colony and the bees will clean and polish every cell in a matter of a few days. Worker bees always clean old cells prior to re-use anyway, so this is not an unnecessary burden on the bees. The bees are very thorough and, after they are done, the combs can be used for brood or honey production. It’s amazing, but no taste or smell of mold will remain on the combs.

Rusty

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Comments

Nancy
Reply

Interesting clarification on what came first, the mold or the dead bees. Re: reusing old bee equipment. I take it by your post you’d say “Forget it” if it was foulbrood or CCD?

Rusty
Reply

Nancy,

Right. We know American foulbrood can be transmitted on old comb and should be burned. Even though we don’t know what causes CCD, reused equipment appears to infect bees who move into it. In either case it is not worth the risk. Plain old mold, however, is not a problem.

Susan
Reply

Good to know. I lost one of my hives last summer & it smelled fermented & was abundantly moldy, but I don’t think it was AFB. I was looking at replacing it but maybe I will try airing it out. Thanks!

Seonaid
Reply

Thank you so much. This is exactly the problem I was having today and I wanted to let you know that I appreciated your work.

Lisa Henry
Reply

Exactly what I was looking for. As a new beekeeper, I thought the best thing to do with the drawn out supers that the bees cleaned last fall were all dry and double bagged them and put them in the basement – they would be fine – WRONG! lol

The 6 drawn out supers that we have are going on the porch today to start their drying process…..we are going to get some rain so we’ll be sure to bring them in – hopefully the stink will be gone by then!

Rusty
Reply

It’s amazing how much moisture is in frames and combs. They look and feel dry, but once you seal them up they mold in no time. I think most of us have done this at one time or another, so don’t worry. But the moldy smell won’t go away until the bees have cleaned them up.

Andy
Reply

What about the processed honey supers? Is there a proper way to store these during the Winter so that they don’t get the mildew build-up on them? I live in the Pacific Northwest. It’s hard to keep the mildew from building on the foundation, even though I try to keep them where air can pass through them.

Rusty
Reply

Andy,

The best way is to let the bees clean them up after extraction. You just put an inner cover with a center hole over the top brood box and then put the supers of wet frames on top of the inner cover, and put the lid (roof) on over that. The bees will clean up every last drop of honey and take it down to the brood boxes.

The problem is that it is getting too late in the year for that because the bees are starting to cluster. It is best to do it right after extraction.

If you have room in your house, you could bring them inside. Your furnace, wood stove, or whatever you use to keep warm keeps the air very dry in winter and the combs will not mold. It’s the only way I know of the keep the mold away other than letting the bees clean them up. Sheds, garages, cellars, etc. are usually to cool and damp for good storage.

Andy
Reply

Thanks Rusty,
I do let the bees clean them out, but I’ve been doing this by just leaving the supers out in the open where the bees can get at them. I’ll start doing as you suggest, and put them back on top of the brood boxes. that sounds like a great idea.

Lindy
Reply

Hello Rusty and any other people who may have something helpful to say,

I have recently bought two lots of beautiful lilies for vases in my house. I noticed that they have enormous amounts of pollen on the stamens so on 26th December I took about 14 of the flower tops with stamens intact to my two hives; I thought it would be a treat for my bees on what we call 2nd Christmas Day. Then, later on when I had been home awhile, I wondered if I had done a stupid thing and that the flowers may have been contaminated with an insecticide nicotinamide substance.

Has anyone ever tried this before as a pollen provider or is there always a big risk because of not knowing what has been used on those flowers by their growers? I did ask my bee course teacher and he said the risks would be if the bees could choose from fields of contaminated lilies but that so few flower heads probably would not be harmful. I do so hope he is right…..

Very good year ending to all readers and a fine and buzzy bee year in 2013.

Rusty
Reply

Lindy,

Pollen can be contaminated with pesticides, especially when systemic types are used. However, a small number of flowers, even if they have contaminated pollen, won’t make any difference. These pesticides are measured in the parts per billion, so it takes many, many flowers—thousands upon thousands—before you get enough build-up in a hive to affect colony health. Don’t worry about it; you did nothing wrong.

Tricia
Reply

Thank you for your previous reply to my questions!
In regards to your latest article about mold, I have a question . . .

I lost a hive this winter due to starvation. I’d like to re-use the nice comb on the frames but there are some frames with dead, soft, brownish brood; how can I clean those in order to re-use the frames on a new hive next spring?

Or should those frames get new foundation? Besides the dead capped pupae, there are also dead, white larvae. When trying to remove some with a toothpick they appeared kind of tough and can not be fully removed without leaving behind some remainders in the cell . . .

Your input will be greatly appreciated!

Rusty
Reply

Tricia,

This is too hard to answer without actually seeing the comb. If the colony really did die of starvation, the comb would be fine to use. You can just give it to the new bees and they will clean it up for you.

However, if they died of a disease, especially one of the bacterial infections like AFB or EFB, you don’t want to re-use the comb because it will reinfect your bees. Dead white larvae aren’t usually a problem, but there could be a question with the “dead, soft, brownish brood.” It might be okay or it might not.

If it were me I would be wary of any colony death where you aren’t certain of the cause and you have suspicious-looking dead brood. I’d rather be safe than sorry, so at least think it through before you make a final decision. The cost of some new foundation is trivial compared to the cost of new bees.

janece
Reply

Do you have any pic of foul brood? Lost my bees now I have some really nasty looking frames and am not sure what it is.

Rusty
Reply

Janece,

If it is mold, you shouldn’t worry. I don’t have a good picture of foul brood, but the cappings are usually sunken and brown, often with holes in them, and the frames smell horrific (like a dead animal carcass). If you have a close-up photo, I could take a look for you.

janece
Reply

The caps are rounded and very black; in some of the open combs there is yellow jelly like substance in the bottoms. The black is covering a lot of the combs; will try to get a pic and send you. Thanks for all your help.

janece
Reply

I have no sense of smell so I couldn’t tell you how they smell .

mbee
Reply

Rusty, do you recommend sterilizing equipment when the probable cause of death is Nosema, most likely N. ceranae? I’ve read that the spores remain viable for years. I’m planning to scrape and bleach the boxes, but what should I do with the combs that have various combinations of capped honey, fermented honey, moldy pollen, and empty wax cells?

I’d like to use what I can where I can without the risk of infecting another colony. Is the capped honey okay for human consumption? Can I shake out the uncapped fermented honey and use the wax for candles? Is there a way to clean out the moldy pollen so I can use that wax too? Help!

Rusty
Reply

The way I understand it, Nosema spores (both types) are pretty much everywhere, and they are contracted by colonies that have become weakened by something else. It could be compared to the common cold in humans: the viruses are everywhere but we don’t always contract the disease. As such, I think that just general hive sanitation is appropriate.

If you want to be especially careful, your idea of scraping and bleaching the boxes is probably more than sufficient. If you don’t want to reuse the wax combs, you can harvest the honey (definitely safe for human consumption), and you can certainly melt the comb for candles, etc. If you tie the moldy comb and pollen in a sock or pantyhose submerged in boiling water, the moldy pollen will remain in the sock and you can use the wax. You may want to keep the moldy batch separate from the rest. Once it separates you can decide whether or not it has a discernible odor. If it does, you can save it for some application where it doesn’t matter, rather than using it for candles. If worse comes to worse, you can always use it for fire starters. My husband made waterproof dressing for his boots out of some like that.

mbee
Reply

Thanks, Rusty. Just the information I need. Yesterday I harvested the honey; today I’ll deal with the wax. Love the sock tip for separating out the mold.

Nana Coug
Reply

Thanks sooooo much for everyone’s contributions. I was overwhelmed pulling my two dead outs apart and trying to decide what I could salvage. Mold everywhere. I’m in the Pacific NW and we have humid weather for at least another month. I have frames stacked in the basement now and a fan turned on them. I initially thought I would have to toss and start over.

Rusty
Reply

You are certainly an optimist. One month? I count March, April, May, June . . . maybe I’ve lived here too long, but the wet seems to go on forever!

Cindi
Reply

Dear Rusty,

I started my first hive last April. When I checked both brood boxes this week in February, I found the top deep super to be beautiful and alive with bees; the frames are full of capped honey, capped brood and pupae. Nearly all the frames were full. Imagine my surprise when I got to the bottom brood box and found mostly empty combs or combs just pulling comb out and then two or three frames with grayish green mold over what seemed to be dead brood. I do believe the queen and most of her worker bees and drones moved upstairs. Is that possible?

I took all of the frames out for inspection. The worst of the molded frames I brought in the house and sprayed with a mild bleach-water solution. The bottom of the bottom super also looked like it had mold on it. I fed the colony and boxed it up but did not yet clean out all the other frames or scrape the moldy bottom. Is there any danger to the rest of the colony at this point? Will it get stronger and be able to clean up the bottom super? Should I rotate or replace the moldy super in some way? Since one whole brood box is active, I don’t think anything has killed them but I am not sure.

Thanks for any help you can offer this novice!

Rusty
Reply

Cindi,

Bees move up in winter; that’s just what they do. They more or less eat their way through the honey as they go. When you think about it, it makes sense because bees store the bulk of their honey overhead in the supers (superstructure), not in the brood boxes. So I would be surprised if you didn’t have an empty brood box at the bottom.

The mold is of no consequence. It grows in the damp environment of the hive, especially where the bees are not cleaning it up, as in the empty brood box. As the colony expands again in the spring, the bees will clean up the mold in no time and you won’t be able to tell it was ever there. When we try to clean up the mold we are just applying our own standards to the cleanliness of the comb. But the bees will take care of it when they are ready and to their own standards.

I know, it feels weird or even irresponsible to give them moldy comb, but once you get used to it, it will seem normal to you.

Deborah
Reply

Elsewhere I had read that yellowjackets can destroy a hive. I have just ordered Praying Mantis to rid my garden of a cricket problem, and read that they also eat yellowjackets.

I am not a ‘hiver’, however the people that I buy honey from have been nice enough to give me honey comb to render into wax. The question: the black wax with dead larvae in it (it doesn’t stink) does not seem to render wax. Are there any uses for the dead bee larvae once rendered down? (No, unfortunately I do not have chickens, and the wild birds do not seem interested).

Thank you in advance.

Rusty
Reply

Deborah,

The dead larvae, cocoons, and other debris is known as “slumgum.” Beekeepers sometimes use it to attract swarms to a bait hive. Otherwise, you can use it to start fires. If you have a wood stove or wood-burning fireplace, it will get a fire going in no time.

Liza
Reply

Attached is a link to some photos of what I found in my hive today. I noticed there was no activity this spring, so I opened it up. Very mysterious situation with some dead bees on the floor, and other dead bees in various places in the hive, some on the comb as if they are just walking around, others in small clusters. One cluster I brushed away and found the underlying cells containing full grown bees face in to the cells (all dead). No queen or significant volume of bees anywhere. Like a scene from Pompeii, they seemed just frozen in time.

My main question (other than What Happened?) has to do with the mildew looking powder on the surface of the capped honey. Can I use this honey and how should I remove the mildew (if that is what it is?).

Thanks everyone for your help.

Rusty
Reply

Liza,

My best guess, based on the photos, is that your hive became queenless sometime during the fall or winter. Why it went queenless is impossible to say—she may have had poor genetics, she may have suffered an injury, become ill, or perhaps was weakened by mites. At any rate, without a queen to produce brood, the colony became smaller and smaller until it was no longer able to form a cluster large enough to keep itself warm. There are few dead bees in the hive because the remaining bees cleared out the dead bodies until they no longer had the strength to do so. You didn’t find the queen because they removed her after she died.

The dead bees in the cells with their tail ends facing up starved. They were trying to lick out the bottom of the cells, but there wasn’t enough food to keep them going. Even though there was honey in the hive, the cluster was too small to keep warm. Cold bees can barely move. Just like any animal, they become stiff and unresponsive when their core temperature drops too low. So even though food was a short distance away, they didn’t have the ability to go that far.

The ones that died “going about their business” probably attempted to go in search of food, but they couldn’t make it because of the cold or because of weakness due to hunger. Your description of “frozen in time” is apt.

Some of the white stuff in the cells looks like crystallized sugar syrup or honey and some looks like mold. In either case, just reuse these frames when you get your new bees. They will clean it up in no time.

The grayish powder may be mold or not. What I would do is smell it carefully. Also run your finger along it and see if it comes off on your finger. If it doesn’t come off and doesn’t smell like mold, go ahead and extract if you want. If it smells moldy or leaves a powdery residue on your finger, I would not extract it because it may make your honey taste like mold. Instead, just save it for your bees. They will clean it up in just a few days and, as a bonus, the honey will get them off to quick start. Remember that mold on honeycomb is not dangerous or bad for you or your bees. It is more a question of palatability. The bees will clean it up without a trace, but we humans are not so skilled at that.

Liza
Reply

Thank you so much Rusty, for your insight and expertise. I really appreciate your very extensive and detailed answer. There is so much to learn. Thank you for sharing!

Scott Gibbons
Reply

Rusty, I will be installing a package shorty, and was wondering if I can use frames of honey to feed them from another hive that did not make it through the winter?

I have about six frames of capped honey (brood chamber sized frames) that I was thinking about using in lieu of sugar syrup to feed them if that is OK?

Was also wondering if I should feed them with an inner cover with a hole between two brood boxes to start, or to just add the second brood box with the honey frames right away or a couple of days later?

Thanks, Scott

Rusty
Reply

Scott,

If you are lucky enough to have frames of honey to feed a new colony, it is by far the better choice, as long as you’re confident the colony did not die of American foulbrood. AFB can be transmitted to a new colony through the honey, but other than that, you’re good to go. Whenever I start colonies on honey they build up fast and strong, which makes sense.

Forget the inner cover and put the box of honey on right away. Reduce the entrance to protect them from robbing, at least until they get established. Other colonies in the area may catch the scent of the honey, so give them just a small entrance to start.

Scott Gibbons
Reply

Thanks Rusty, I will follow your direction. Thanks for the call out on the entrance reducer as my neighbor has 3 hives up here in the West Hill in Auburn, WA.

Scott ;-)

Bonnie
Reply

Rusty, we have a hive that died this winter. I just opened it up and there is lots of capped honey, there were clusters of bees on several frames that had started to rot, (been dead for a bit) there was also a few in an area that looked like they just died. I am thinking the hive froze after reading your comments or lost the queen and the fresh ones could be from our other hive? I have bees ordered and would like to reuse the frames. How do I tell if they died of AFB?
thanks

Rusty
Reply

Bonnie,

First off, the hive will smell really, horribly bad. The smell will just about knock you over. Second, you do the ropiness test. You stick a matchstick in a dead brood cell, and when you pull it out it makes a long rope of goo. You can find directions here for diagnosing the disease: http://www.spc.int/lrd/ext/Disease_Manual_Final/b452__american_foulbrood.html. Based on your description, I’m guessing you do not have foulbrood.

Jay
Reply

Hello! I’m very new to the hobby and I just had some questions in regards to what to expect in the future. A lot of my concern is in regards to keeping bees from swarming due to being overcrowded. I’ve read various posts that said if your bees work from the bottom super up to the top one, you can place the top super back on the bottom and reuse the old super. That made sense until I read that bees will reuse their old comb? I was in the mindset that I would be washing/cleaning the old bottom super in order to be reused. In that mindset, there would be no overcrowding ever as long as you stayed on top of cleaning everything. But when I read that they reuse/fix their old combs now I’m confused. I understand that during honey flow, you put the top supers on so they can store their honey in. How would you go about making more room for the bees before they wanted to swarm? (Without having to buy many many extra supers to add on) I am starting with two deep 10 frame supers and 2 medium supers (for honey collection only) I live in New York State where the winters can be cold and snowfall abundant. Thank you for the info and advice! Greatly appreciated.

Rick van vliet
Reply

Thanks for a great thread. Lost a colony during a long, crappy, snowy spring in Minnesota. They were alive in mid-march, started feeding 1:1 syrup, but they died sometime in the last few weeks when we had lots of snow. Guessing that they went queenless and just couldn’t keep their numbers up. Moldy frames, but not the stink of AFB. I’ll look closely, but will probably dry out these frames and get them back into newly-packaged hives after a couple of weeks (packages installed 26 April).

Cherokeescot
Reply

The only way to be sure about the type of mold is to destroy the spores completely. That way you have no worries. Here, its a simple operation. Place a number of frames in a large plastic trash bag. Place an Ozonator inside the bags making sure none of the vents are blocked by frames or plastic and unable to suck in or discharge.

Leave in for two days on high or ‘away’ mode. This completely eliminates mold, virus and bacteria.

Rusty
Reply

…until the instant you remove them from the bag.

Rebecca
Reply

Rusty,
I’m just getting into beekeeping. I bought a ton of boxes, frames, etc at an auction. The frames all have old comb on them, and I don’t know how old it is. I don’t have any history on the hive. I know I’d be risking a disease, but I was wondering what your thoughts were on trying to reuse everything as is? Is there a time limit to how long combs can sit, then be reused? Is there anyway to tell if they’re too old? Also, reading one other post, if I use a super on the bottom for a brood box, then the bees move up into a smaller box, do I somehow have to get them back into the super in spring, or can I just take it for another set of bees and leave them the littler boxes? BTW-your info is fantastic. I’ve been searching everywhere and finally found several other answers right here. Thanks!

Rusty
Reply

The real problem with old equipment is American foulbrood. But if the comb doesn’t contain dead brood, it is probably just fine. So I would check it for dead brood and then make a decision. Bees prefer old comb, although if it hasn’t been used in a while, it probably no longer has the odor of bees. Old comb is more brittle than fresh comb, but that isn’t much of a problem either. There is no pull date on comb, so if it is not diseased it will do the job for you.

Generally, bees move up in the winter, down in the summer. They will get there on their own. If you want to speed things up, you can reverse brood boxes, but you don’t have to.

Alicia
Reply

This is a great post. Very useful since I lost both of my hives this past winter and had a bunch of perfectly good comb left. One smell I am curious about is dirty socks. This is a smell I get with some of the frames with uncapped nectar, and I don’t think it was the pollen?

I was also wondering if it was okay to use frames that have had wax moth droppings on them, but the moths themselves had been disposed of? On that same idea of pests another issue I was curious about was ants, cockroaches & earwigs. They have moved into the area where I had the cleaned out hives, and this is where I have my new hives…what is the best solution without affecting my new bees, or maybe I should restate is there a solution? I wasn’t sure if diatomaceous earth would be harmful to the bees if i spread it around the outside of the hive.

Rusty
Reply

Alicia,

Sometimes when you have uncapped honey, you get fermentation. That is probably what you are smelling.

Honey bees are clean freaks and a strong hive will be able to clean up insect frass, droppings, and live and dead bodies. They can do this much more efficiently and effectively than we can. The material from your cleaned-out hives will soon decompose into the soil. I wouldn’t worry about it.

Some people use diatomaceous earth around their hives. About the only bees that get into it are those that are already weakened and dying.

Julie
Reply

Rusty -

Wish I’d read your site before yesterday when I took apart the frames with mold on them. You say I could have used them (I know the hive died because it lost its queen and there were too few to keep the place warm). But some of the wax on the frames was so brittle. It just crumbled; not at all wax-like. Could those really have been used again? I can probably retrieve some from the trash (I broke them apart to make them fit my small bin – argh!), but I’m wondering if they really can be reused in such condition. Will the bees remove brittle wax?

Rusty
Reply

Julie,

Yes, the bees will fix them up. How cold was it when you were working with the frames? The wax is extremely brittle in cold weather but softens as the temperature rises. If the bees have preformed comb, it saves them a ton of work, even if they have to clean it up first and mend it. Exuding all that wax requires much energy and therefore much foraging just to make comb. A colony on preformed comb gets a huge head start in the spring and will be able to store much more honey over the course of the year. One thing I learned early on is that drawn comb is the beekeepers most valuable asset.

You shouldn’t worry about the brittleness; that’s for the bees to worry about and they will know how to handle it. As for cleaning moldy combs, it only takes a day or two to get everything cleaned up and shipshape.

I do think, however, that old black combs should be replaced every four or five years, a few at a time.

Becca
Reply

I had a hive die this spring, too, (I think a lot of water got in the bottom and eventually the queen died too and the hive just dwindled in April) and the top super was full of honey, but the lower two were abandoned, and moldy. The comb was blackened and also really brittle and kind of shiny and papery, as if it was made out of insect wings. It bent more than crushed like wax. Sounds maybe like what Julie had going on? Insights? Thanks!

Rusty
Reply

Becca,

That sounds normal. As wax ages, it loses volatile compounds and becomes papery. The bees can still use it though; they will clean it and strengthen it with new wax.

Lisa
Reply

Hey Rusty,
I am a newbee that lost a hive over the winter – I think something mysterious happened to the queen and they died out. There was a lot of honey left, no dead brood, no dead bees but maybe a dozen or so when we first opened it up. We are extracting the left honey as I type – we are moving out of state and will be gifting our hive and frames to the local beekeeping club, but wanted to eat and give away some of the honey. There appears to be black mold over the comb in places. Is this okay to eat? It is honestly hard to tell if it is mold or just debris if the bee variety. An experienced beekeeper with our association came to look at the hive while we weren’t around but he passed a message along agreeing that he thinks something happened to the queen and seemed fine with loaning us the extractor, so I am assuming there is nothing to be concerned about. Just being new to this, I thought I would pick your brain. I tend to err on the side of eating things if they seem moldy anyways but this is a new world for me. Just want to be sure there isn’t something freaky I might be eating or sharing with loved ones. Thanks!

Rusty
Reply

Lisa,

I think it will be just fine, especially since you are extracting it anyway.

terri
Reply

Hi Rusty!

I have a new hive that had fresh foundation in the frames. On one, the cut comb sheet must have broken and the bees are building wacky comb on it which looks like a rolling wave with cells built under the crest and on top of it. It still fits together with the other frames and it has brood in the cells. Can I leave it as is, or should I take it out and replace with fresh foundation?

Rusty
Reply

Terri,

I would just leave it. Things like that happen all the time.

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