postmortems & mysteries

What crud is this?

Foundation with crud. Mark Wilson.

Here’s another mystery for all you hive detectives. Mark, a soon-to-be beekeeper in northern California, purchased three beehives from an ex-keeper who decided to quit after his bees absconded. Mark performed a cursory inspection of the equipment before purchase, but after getting it home and examining more carefully, became concerned about the crud shown below.

Being a cautious individual, Mark is concerned that the seller may have had a brood disease—well, not the seller but his bees. He wonders if the seller might have scraped the comb free of evidence before the transfer.

According to the seller, the colonies were productive, but after a winter of neglect, disappeared without a trace. He also said they were not diseased. But Mark says out of all three hives only a few frames had a little bit of drawn comb on them. The rest were either undrawn or scraped clean.

So where is the comb? Why would he scrape it all away? Some wax moth cocoons were evident, but not many. Perhaps the comb had been destroyed by wax moths and the mess cleared away because it looked so bad?

The photo shows one of the plastic frames and the crud. In my mind, it looks like the remains of old brood cells and some dried up pollen. Mark wants to know what to do to ensure the health of his bees which he hopes to get next spring. Your insight, comments, theories, suspicions, and advice will be greatly appreciated.


Foundation with crud. Mark Wilson.

Plastic foundation with crud. © Mark Wilson.



  • Rusty,

    That is weird indeed. Could they have all vacated due to the wax moth/disease? I am only a second-year beekeeper and I am perplexed as to why they would not have drawn any comb. It looks way too clean for the previous owner to have “scraped clean.” It looks as through they never drew any comb. Too clean to have been mice wiping out the frame and no chew marks. Maybe the possibility that it “could” have been so hot inside the hive that after the bees vacated that the wax could have melted away? Naw, that does not sound right either. I don’t know. Would love to know if the mystery gets solved.

  • Looks like a wax moth infestation. I had it in one of my hives after the bees absconded and I didn’t notice for a couple of weeks. When I scraped the comb off, it looked just like that. I even remember the pollen stores looking the same, like crumpled up cake where the larvae had been.

  • Just a guess. The beekeeper may have scraped off all of the wax moth infested comb because he didn’t want to sell nasty looking to a new beekeeper. Or it may have just fallen off as very infested wax moth comb looks, especially on plastic foundation.

    The dark, non pollen spots may be propolis from the bees. Maybe in an attempt to place a barrier between the plastic and the honeycomb.

  • The fuss is, if it is a brood disease like foulbrood, the whole hive is contaminated by the spores, not just the frames. I’d infect any bees I put in the hives and potentially infect nearby hives. I know there are other beekeepers near me.

    • Mark,

      If foulbrood is present, combs and frames must be destroyed but boxes can be sanitized with a propane torch.

    • Ditto.
      Just pollen and cocoon remnamts. One interesting thing with plastic foundation is the wax and cocoons often lift right off the plastic clean leaving the pristine plastic. But often, it sticks and leaves what you see there. I’ve got a number of frames where I didn’t get my honey extracted before wax moths made homes in it. So areas where the wax moths were, we had to take a drywall scraper to and in those areas, the wax lifted up and looked just like this.

      I’ll be reusing mine as-is next year now that the damaged ones have gone through a freeze-cycle. So personally, I’d reuse the frame shown above as-is. Although if there’s little to no wax built up on any of his inherited frames, I’d want to start with nucs, not packages so each colony had at least 5 drawn frames to live on while cleaning up the frames he has.

  • This isn’t the way wax moths trash frames. Here’s an image of that:×510.jpg

    This is likely chalkbrood, which is caused by poor ventilation. There’s not much in the description, but if the mummies are hard and not soupy, chalkbrood is the likely culprit.

    You can bleach the frames, if you wish, but like an earlier post suggested, frames are cheap. The boxes can be wiped with a bleach solution, but it’s not necessary. Just remember to provide adequate ventilation.

  • Rusty,

    Looks like chalkbrood mummies to me a pathogenic fungus that attacks the gut of developing brood Ascosphaera apis, fungal spores that are super contagious that thrive in cool, damp places! Looks like the end to those bees and the hive would be burnt by me if they were mine!

  • I ran across exactly this same thing at my son’s dead outs in S. Texas. Pollen remnants, black cocoon debris, and bare white plasticell foundation. I popped out the foundation, burned the frames, and charred the box innards. The plasticell I took to the car wash, and blew all the debris out of the foundation, and put back into new frames. Then I brushed a thin layer of melted beeswax over the foundation, and put it back to work. My best guess is Mark may have been a victim of absconding due to varroa mites, small hive beetle, or possibly pesticide damage. Hard to tell from what was written and shown.

  • I don’t think this photo reveals enough to diagnose anything concerning a brood malady. Also, without the infected cells to examine for foulbrood scales and other remnant evidence it’s just guessing. But the fact that the seller went through the work to scrape some of the frames is curious. The story is suspect also- why would all three colonies abscond? Die I understand, but all of them leaving…why? I think this illustrates all the reasons why used equipment, purchased from someone you have no reason to trust, is almost always suspect unless you can inspect it in operation with a live colony beforehand. Given what’s presented here, I would not use this equipment without irradiation or as Rusty suggests, new frames in scorched boxes.

  • I don’t want to discourage you. However, don’t buy used equipment. Don’t trust it. My mentor advised me that beekeepers need to be isolationists when it comes to equipment. In my community, a shared extractor might have spread AFB. Exercise caution. Good luck.

  • I have seen this before and think it is rather pretty in the sunlight. I scraped off old brood comb to recycle that was really dry from sitting in storage empty all winter on plastic frames. It came off it chunks that left the foundation plastic white and chunks that I had to peel off while leaving black and silver cocoon membrane on the foundation itself. (Or at least that was what I thought it was) and bits of pollen. I don’t have wax moths here in BC Canada and my hives are brood disease free.

  • It is definitely the remnants of pollen and cocoons after the wax has been scraped off the plastic foundation. In my experience, the bees will not rebuild on the used plastic. Kim Flottum power washes his plastic foundation and re-coats the surface using a paint brush and his own cappings wax (melted of course). Too much work; less work and better for the bees to go with starter strips

    My advice: Scorch the inside of the boxes. Sand the exterior, top and bottom surfaces and re-seal or re-paint exterior surfaces. Don’t reuse the frames or foundation; buy new frames with or without foundation and, if without foundation, insert starter strips.

    Better safe, than sorry for saving a few bucks.

  • I agree with Rusty’s original assessment.

    Mark could contact the USDA Bee lab to see if they could test the crud if he were able to scrape enough out. They normally do comb samples for free, but ask for a minimum 2″ x 2″ of comb. But if they were willing to test an equivalent amount of crud, that could clarify if any diseases are present.

  • I don’t use plastic foundation anymore, but in the past… I have cleaned up plastic frames like this and paintbrushed melted beeswax on top of the bare plastic areas of the foundation. The bees rebuilt beautiful comb on top of it again. If you leave bare plastic foundation in the hive…I’ve found that the bees won’t touch it

  • P.S. I also wanted to mention that Sarah Currie’s comment is spot on! Refrain from buying used material whenever possible and she’s also correct in making it a point to mention that even a shared extractor can pass on (share) contaminants.

  • Up here in Vancouver, the beekeeping associations share the cost irradiation runs, and both my beekeeping mentors recommend that if you’re getting equipment from someone you don’t know, best to get it irradiated. That way you could do the whole lot and use it. If you can’t do that, I wouldn’t use it – too much heartache.

  • Erin and Rusty,

    They have a company by me that has a ” Apiary Day” in March. They use Electro Beam Irradiation, same thing hospitals use to sterilize surgical equipment. The nice thing about it is you can save the comb. This has been practiced on the east coast for a decade and they state that there bees do fine. This company charges five dollars per box. It will get rid of European and American foul brood. Ask your local hospital where they go. Maybe they can help.


  • Looks exactly like my equipment, after I scraped it after a wax moth infestation. But better safe than sorry.

    I guess he can’t just ask the beekeeper himself because he doesn’t trust the answer?

  • Another option (of it’s been mentioned already, forgive the duplication), is to pop out the plastic foundation and replace it with new. This assumes the frames are wooden. BEFORE adding the new plastic, use a steamer (lots of videos showing how to extract wax using a steamer) to sanitize not only the wooden frames but also the hive body. Replace the plastic foundation in your newly sterilized equipment.

  • If it’s AFB the frames, bees, hive etc. (whole lot) have to be destroyed by fire (at least in the UK),
    If it’s EFB the frames, and the bees have to be destroyed,

    A good way of killing the colony, is at soon after dusk, close up the hive, pour in a cup of petrol, leave overnight, next day, bees will be dead, if AFB, more petrol and burn, if EFB remove frames from the boxes and burn in some sort of incinerator e.g. a drum with suitable ventilation holes at the bottom (~6 will do, 2…3 inches triangular – cut with an angle grinder, or holes made with a pick axe etc.).

    Making the incinerator is a good way to work off the frustration of having your first dead/diseased colony 🙂

  • So why can’t the – plastic frames – be ran through a dish asher a couple times – and then rinsed super well? Heat gun all the interior of the boxes, cracks really well and then use them?

    Some of it ‘looks’ like dried up pollen – but a lot of those other cells – they look really sketchy.

    • Monica,

      It depends what you think is in there. I wouldn’t use that method if you suspected AFB, but as a general clean up it would work well.

      • I remember seeing something like those pics in a friend’s hive about 15 or so yrs ago. He kept bees all over CA. We had gone to his bee yard to check a couple of failing hives. I remember he lost many hives, one after another. The other thing I vaguely recall was a really bad smell.

        The whole day stuck sharply in my mind because of how MEAN his beez were. They came after me 60 feet away, before I even got near the hive. They covered my veil so densely I could hardly see out, I could feel the vibration and weight of them on the suit and gloves. And the sound and scent they made – unforgettable.
        The suit and gloves must have been stung hundreds of times.
        I digress – sorry.

        So if I understand – if one has the bad luck of AFB, then basically everything needs to be burn piled asap? So is AFB a virus or a spore?

        • Monica,

          AFB is caused by a spore-forming bacterium. Although it is best to burn the comb and frames, the inside of the hive can be scorched with a propane torch, treated with ethylene gas or ozone, or soaked in bleach.

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