Adventures of an Amateur Mason Bee Keeper – Part 3

By Debbie Palmer | December 21, 2017

cleaned cocoons ready for winter storage

Prepping cocoons for winter storage

Yikes, October already? Time to clean cocoons! Well, it was time, but I didn’t actually get to it until early November. Jerry Paul reassured me that this was okay, that you can clean your cocoons any time over the winter as long as they have been kept cold. The location I’d been storing them over the summer was now too warm, so mid-October I moved them downstairs where it was consistently cool (58-60 degrees F) until I could get to them. That’s not “cold”, but I knew it was only going to be for a couple weeks, so I figured it was sufficient.

Step one – open nesting tubes to decant cocoons

If you’ll remember from my prior posts, I used a combination of commercial cardboard tubes w/paper inserts and teasel tubes which I’d collected from nature. No matter what nesting material you use you’ll want to do this activity in or over some sort of tray or pan in order to collect all the cocoons and detritus you’ll be generating. It’s a messy process! And if you are pollen or dirt/dust-sensitive, I’d recommend wearing a dust mask. This only occurred to me after the fact, when I noticed an increase in sneezing and, well, let’s just say “sinus activity” and leave it at that.

Let’s start with tools. Here’s what you’ll want to have handy:

  • a small dowel or stick, preferably tapered wedge-like at the end, similar to a cuticle stick (I happened to have a wooden clay tool of the perfect size) for pushing cocoons out of split-open tubes. In a pinch you can use a phillips screwdriver, or even your finger
  • a jackknife for splitting open teasel tubes
  • needle nose pliers (for pulling the occasional recalcitrant paper liner out of it’s cardboard sleeve)
  • a skinny stick, like bamboo skewer (optional; it’s for cleaning the back-end hole in cardboard tube sleeves)
  • an old toothbrush (extremely optional) – will explain later

Opening the paper tubes. Thanks go to Jerry Paul for advising me to pre-split the paper tubes before loading them into their cardboard sleeves in the spring! I was now at the stage where this extra bit of work paid off, as I could just slide the tubes out then gently pry them apart along the split to reveal the cocoons within. If I hadn’t taken that step, I would have had to peel the tubes open in a spiral – a lot more tedious, messy and time consuming!

Opening the teasel tubes. The goal here is to split them such that they pop open lengthwise along the grain. This is where the jackknife comes into play. Carefully insert it into either end of the teasel tube until it starts to split, then twist the knife and pop it open. The trick is to not insert the knife so deep that you cut into any cocoons in the process. Fortunately the mud-cap end usually has an air gap behind it before the first cocoon. I found the mud-cap end to be problematic though, as the teasel is more fragile at that end and often would snap off in pieces rather than split. So I experimented with splitting it from the back end instead, to much greater success. The back end is stouter because of the natural end-cap “joint” there. You have to be more mindful of the cocoons if you split from this end though, as sometimes there are ones right at the very back. Fortunately the females always seal the very back with a mud wall before placing her first pollen ball and egg, so this offers some protection for that cocoon. Just take your time and ease the knife in slowly. You’ll get the hang of it.

Split teasel tube

Decanting. Once you’ve opened up a tube, the next step is to gently scrape the cocoons out so that you can gather them up to be cleaned. Use the dowel for this: run its tapered edge back-to-front along the length of the opened tube, angling it downward like a tiny shovel so it goes underneath and dislodges the little mud walls and cocoons up and out (you don’t want to push them end-on, mooshing cocoons into each other). Sorry I don’t have a picture for this; I needed both hands to do the work and didn’t have a third one handy for holding the camera! I think you get the idea though. The cocoons’ backsides are cradled by the concavity of their little mud walls so are somewhat protected, and I see on the Crown Bees website they use a phillips screwdriver when cleaning the wooden nest blocks, so I suppose you could use one to clean nesting tubes too, as long as you were careful.

mud walls are concave

The “skinny stick”. If you look at the back end of the cardboard sleeves, there is a tiny hole there. Often, the bees will mud that closed when they build their first mud wall. Since I want to reuse the sleeves (with new paper tubes, of course), I want everything to be a clean and sanitary as possible. So after removing a tube of cocoons I would always check that back end hole to see if it was plugged. If it was, I’d take the ‘skinny stick’ and poke it from behind, tapping the tube to so the plug falls out. Then I’d flip it around and look inside, checking against the light to see if it is completely clear. Once or twice after poking it out I didn’t see light, so I poked it some more and a cocoon plopped out! It had stuck in there and stayed behind when I pulled out the tube, so it is always good to check!

the closed and open ends of a paper tube

The toothbrush. A couple of the teasel tubes which not only split open cleanly but also were filled to capacity with cocoons I decided to keep and reuse next year (I’ll rubber band them back together). It’s just going to be an experiment, to see if something about them was particularly good for nesting (optimal size?). So I used the toothbrush to scrub the halves clean. Wooden nesting blocks are vigorously scrubbed with a scrub brush after decanting cocoons, so I just projected that concept onto the teasel tubes – albeit with a smaller brush!


Before even opening the tubes, I noticed something interesting: my bees seemed to have more than one mud source – note the three different colors!

three colors of mud were used

When opening tubes, in addition to cocoons and mud walls you will find other things. Most common are frass, pollen mites, and unused pollen balls (pollen and nectar, actually). Frass looks like mini chocolate sprinkles that have piled up between cocoons and mud walls but is actually bee larvae poop. Remember, these are living, growing creatures; think of babies and all those diapers! Pollen balls are waxy yellow-brown lumps (think: giant earwax ball). Pollen mites, on the other hand, are loose, yellow-orange in color, and fuzzy or fluffy.

the contents of a cocoon-filled teasel tube.

In one teasel tube, I found a desiccated earwig in the back. Some female had walled the unlucky guy in à la Cask of Amontillado! Good for her, I say.

Far less savory: in another tube, indications were that there had been four egg chambers, but there was only one cocoon; the other three chambers had small, dead grub-looking things in them! Yick. On closer inspection, the singleton cocoon seemed dry and papery (it made a crinkling noise like it was empty when I went to remove it), so I decided to open it, see what I could see. Couldn’t tear it open with my fingers – the cocoon ‘wrapper’ was remarkably tough material! – had to use an xacto knife. Sure enough, inside was another black, hard, dry grub. I went online to see what I could learn about grub pests in mason bee nest tubes and couldn’t find anything. Then I queried “mason bee chalk brood” and was alarmed to see a picture of chalk brood ‘cadavers’… one of which looked similar to what I’d found.

dead, dried up cocoons that look like chalk brood tainted examples.

Talked to Jerry about this, and watched a small video on the Crown Bees website about chalk brood in nesting blocks and we’re just not sure… Jerry thinks it may be a different pest of some sort, as he has come across these ‘grubs’ as well. He’s going to hang onto some in a separate container and see if they hatch out into anything. This is what Citizen Science looks like, folks! (Meanwhile I chucked my ‘grubs’, cutting them in half first for good measure, to make sure they were dead.)

One particularly interesting observation was that in skinnier teasel tubes, the cocoons were noticeably “capsule” shaped instead of egg-shaped. I’m presuming this was because their growth was limited by the inside diameter of the tube? Normally, cocoons look like fuzzy, plump little raisins. capsule-shaped cocoon

I think my most interesting discovery was that every tube I opened was different. Tubes I’d assume would be filled with cocoons (because they were mud-capped) were half empty. Generally speaking you are supposed to be able to ID the gender of cocoons by size: the males are small and the females large. But sometimes I’d open up a tube and the size distinction was not at all obvious. There are supposed to be 2-3 males at the outside end with the rest towards the back being female, but by my observation, distribution was all across the board. One tube distinctly had a small cocoon all the way in the back, even though there were larger ones in the middle! Was that a small female, or was it a male? Near impossible to know. Another time, a tube appeared to contain all females (all large cocoons). At least none were close to the opening; there was a substantial air gap between mud cap and first cocoon. Almost always there was at least some air gap behind the mud cap and before the first cocoon. Actually, many times there were large air gaps (no cocoons) at either or both front and back, even though the tube was mud-capped.

Step two – wash and dry cocoons

Now I have to say right up front: out of ALL aspects of mason-bee husbandry, this step was THE most counterintuitive to me! Here we go through all this trouble to keep nesting tubes and boxes from getting wet while out in nature during the spring (remember my 2016 fiasco?), only to bring ‘em in in the fall and dump them unceremoniously into a basin of water… with bleach in it, no less??  No I am not making this up. Stick with me here and learn as I did.

Assuming you have separated all your cocoons from their nesting materials… yes, it is now time to wash them. Time to clean away all the schmutz – the frass, pollen mites and anything else that is not a fuzzy little cocoon raisin. We are not trying to mimic nature here; as I’ve said before, what we’re doing is stewardship. Out in the natural world, cocoons aren’t washed or looked after in any way and mason bees manage to survive, but certainly a large proportion of them are lost to predation, disease and all the other curveballs Mother Nature throws their way. What we are doing is more like organic farming. We are taking optimal care of our charges so that more of them survive to adulthood than they would in the wild. More will survive and thrive and help us and the plant world with their superb pollination skills. But I digress.

While decanting cocoons from tubes, I decided to separate out the little mud walls as I went along, and if a tube contained pollen mites or anything unsavory looking, instead of scraping the whole lot into my work pan I would flip the cocoons out one at a time, leaving the debris behind to be discarded with the tube. But that’s just because it was my first time doing this and I wanted to go slow, observe carefully, see what I could learn. You don’t have to do this. You don’t have to because the wash step will take care of it all for you; you can indeed just scrape everything out of the tubes into the work pan, schmutz and all.

The story is, as a larva is growing, it spins itself a sleep sac – the cocoon itself – in which it pupates, grows into adult form, then rests over the winter until it’s time to emerge in spring. This sleep sac is made of silk and, you guessed it: waterproof!

So you make a wash solution of 1 gallon of water to 1 tablespoon bleach. This tiny addition of bleach is for killing pollen mites and any other potential pathogens like chalk brood so that the bees don’t spread it when they hatch. It’s best to use a white basin or bucket (I used a white plastic dishpan), so that you can see the degree of cleaning going on.

The cocoons are waterproof, but they are not bleach proof, so when you wash them in this solution, you don’t do so for very long. Set a timer for two minutes, dump them in (they will float), then swirl them around gently to disinfect and to dislodge as much junk as you can. When the timer goes off, take them out. A wire mesh strainer works best for getting them out in a timely fashion.

Very important next step: if you washed them in a bleach solution, you must rinse them. I ended up rinsing them twice. The bleach solution did not clean them thoroughly (though it did disinfect). I strained them out, set them aside for a moment while I cleaned out the dishpan, refilled it with clear, cool water, dropped them back in and agitated them some more. After a couple minutes the water was getting gukky again (I wanted clean cocoons, and they were stubbornly holding onto their frass!), so I repeated the the rinse step in yet another basin of clean water.

Now they need to be dried. Spread them out in a single layer on paper towels. You may need to do this more than once too (I did), transferring them to a fresh dry layer of toweling until enough of the main wetness has been removed and they can air dry. How long does it take for them to dry? All depends on the humidity in the room and how much water you blotted away before letting them sit. Don’t try to rush things with a blow dryer or by putting them in the sun or an overly warm spot! Remember, at this stage in their lives they need to stay relatively cool. Leave ‘em out for a couple hours or overnight; that should do it. Word of caution: if you’re going to leave them unattended, be sure they’re somewhere the cat can’t get to! I don’t know about your pets but, given the opportunity, my cat would’ve knocked them everywhere!

cleaned cocoons

Final step – winter storage

Your cocoons are now clean and dry. Time to bed them down for winter. Attention to moisture comes into play even in this last stage. They need a little humidity, but not so much as to cause mold. And they need ventilation. They are living, breathing creatures, in hibernation but not dormant. Find a suitable container, something you can poke holes in the lid of, something that will contain the cocoons in a layer not more than two deep or so. Lay a paper towel on the bottom for them to rest on, then add a small dish into which you can place a moistened paper towel to provide humidity, something that provides a barrier so it does not come into direct contact with the cocoons.

cocoons in container for winter storage
I sorted out (as best I could) and separated the male and female cocoons, so that when I go to put them out in the spring I can be reasonably assured I’ve deployed an even balance of male and female. Note that this is only half of my harvest; I set up two containers – one for future orchard pollination, one for the plants around the house (where I had my two bee boxes last year). Note also the size difference between male and female.

Store your container(s) of cocoons in the refrigerator, then remember to check on them every two weeks or so. Re-moisten the paper towel if it has gone dry, and inspect cocoons for mold. If you see signs of mold, Jerry recommends repeating the bleach-wash, rinse and dry steps, then repacking them to store as before. If I found mold, I’d probably bleach-wash, rinse and dry the container as well, to remove any possible spores, and use a fresh paper towel both under them and in the moisture-providing dish for the same reason.


To satisfy my own curiosity, I spent a fair amount of time trying to count cocoons by tube and by gender. I did so as I was opening up tubes, as well as after cleaning but before storing. Here’s what I observed:

Cocoon counts per tube varied significantly. Alas I didn’t keep track at my training session (where I opened maybe a dozen tubes?) but once I was working at home, the top count was eleven in a single tube! It only happened three times out of over 100 filled tubes (two were paper, one was teasel). There were five instances of ten cocoons in a tube (one was paper, four teasel); eleven instances of 9 per tube (7 paper, 4 teasel); nine instances of 8 per tube (10 paper, 5 teasel); sixteen of 7 per tube (11 paper, 5 teasel); eighteen of 6 per tube (9 paper, 9 teasel); fifteen of 5 per tube (9 paper, 6 teasel); eleven of 4 (3 paper, 8 teasel); four of 3 (3 paper, 1 teasel); one of 2 per tube (teasel), one of 1 (one lonely cocoon at the verrryy back of a paper tube… which was still mud-capped on the end, so it looked full!). I must have missed something somewhere, because my math isn’t coming out exactly right (I just kept scribbles on pieces of paper), and this is probably not a large enough sample on which to make any sort of proclamation, but overall, the distribution was greatest in the 5 to 7 cocoons-per-tube range, which jibes with the generally accepted norm.

In the final tally (I did a recount after they were all washed and dried), I harvested over 750 cocoons (a little over 400 males, and about 350 females). I was chuffed! But then suddenly it dawned on me: I had only deployed 75 cocoons in the spring… EGAD! Those bees multiplied by a factor of ten! Which means I need to provide ten times the nesting space for them by next spring if I want to deploy them all! Fortunately I have other options. Crown Bees will actually buy back cocoons from you, through their bee buy back program. They inspect, clean and store, then distribute cocoons for pollination across the country in the spring (they document what region your bees came from and only sell them back to users in that same region). Alternatively I can donate extra cocoons to Jerry Paul and BSWCD, where they will either be sold as a fundraiser (or given to schools to sell for fundraising), or distributed via the Bee Buddy program. All options are equally good, as we all share the same goal: helping to build up a robust pollinator population in a world where they are threatened by so many things.

Thanks for reading! Hope you enjoyed following me along on my mason bee keeping adventures! And if you’ve been on the fence about mason bee keeping yourself, I hope my experiences have nudged you into taking the plunge. You won’t regret it; it’s a blast!

About the Author

Debbie Palmer

Debbie is a lifelong devotee of fresh and local foods, farms and nature in all its raw, uncompromising beauty; an occasional artist and maker, a daily cook, an introvert, she is happiest when working on something - just about anything - outdoors. She lives on her dream property in Soap Creek Valley with her husband, Ken and their cat, Isabelle Underfoot.

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