Mason Bees: Maintenance and Harvesting and Cleaning

It's that time of year! The decorative gourds are out, the tomatoes are long gone and the nights are getting long. It must be mason bee harvest time! 

This will be a recap of my very recent experience of "harvesting" mason bees (cleaning their cocoons, really) at Chickadee Gardens. We have had mason bees for some three or four years, however this is the first year I have attempted to collect the cocoons for cleaning and safe keeping. Why now? Why not let nature just let it take its course and leave them be? At the advice of several very knowledgeable mason bee keepers, I decided this was the year as cleaning them means more and healthier bees next year. Earlier this spring when I purchased another house for our expanding mason bee population, I did so intending to clean everything when the time was right. Now's the time.

 March of this year I blogged about why one would want to have mason bees in the garden (if you have an orchard, you really want them), you can read that post here which goes over the many reasons to host them, their life cycle, maintenance and more. The most essential reasons are that they are native pollinators and are much more efficient at it than honey bees. Plus, they are the earliest pollinators emerging in springtime to coincide with the blossoming of fruit and nut trees. Cold doesn't faze them, nor do cloudy days. They are very easy, non-aggressive, and frankly quite beautiful with their metallic sheen. I have enjoyed countless hours watching these gentle bees in the garden and with the decline of pollinators worldwide (for a variety of reasons), it's one step in the right direction to host such interesting and incredibly valuable pollinators. 

 To do right by my little pollinators, I wanted to clean up their homes and give them a fresh start for spring. 

 I will warn you now, this was not a fun nor easy task - but it's my own fault as some of the tubes were in place for two seasons and had deteriorated terribly. You can see some of that at the bottom of this older mason bee home, the tubes on the bottom were basically goners. If I had done this last year I doubt I would have had any trouble at all. The reason I didn't do it last year is because as soon as the bees emerged from their tube homes in April, they went right back in and started nesting again. That's why I did this:

  I removed all the tubes. Many of these will not be reused, they were pretty gross. The idea is the white inner tube is the disposable one and the cardboard outer tube is reusable.

 Here are the two nests houses with the tubes removed. I actually uninstalled both of these from the garden shed wall and brought them inside for a thorough cleaning. They are drying in the basement and will go back out to the same places, empty, once they are thoroughly dry.

 So the basic idea is this: Remove the cocoons from their disposable white liners and clean them, store them in a cold place for winter and they will emerge on their own when the time is right. Crown Bees, which is the supplier I used (found at the Backyard Bird Shop in Portland) says not to wash the cocoons but others say yes, do wash them, that the cocoons are very tough and you will wash out mites and other creepy crawlies. I chose to wash them because of the gross factor.

 Now if you are squeemish, turn away from the next few photos. These are the cocoons with little bee poop, mud and pollen in between. Kind of cool, really. So you unravel the white liners and extract the cocoons. Some didn't unravel, so I had to have some help with scissors as some of the tubes were pretty moldy. I think my problems are due to moisture and the fact the same tubes were in one of the two houses for two seasons. I will not make that mistake again.

 I think this orange stuff is pollen. It sure looks like it, don't you think?

 Difficult to see but there are cocoons in there. Each tube should have multiple cocoons in it, the females in back and males in front capped with a bit of mud at the end.

 Here's the damage. There were a lot of tubes with no cocoons or rotted cocoons, just dust. These were the wettest and moldiest of the tubes. The whole task took me about two hours and it was painful in that it was my first try at this, I did not want to harm the cocoons and it broke my heart that so many tubes were moldy. Plus it smelled of mold and was very awkward when the liners would not come out of the brown reusable tubes...I would have to try to cut a notch in the damp brown cardboard to be able to grab on to it to pull it apart.

 Here is the "harvest" (such a strange word to use). Anyhow, here are the cocoons before I washed them.

 This has been dubbed my official cocoon holder. Forever. I cannot use it for anything else ever again. The cocoons float and the debris falls to the bottom.

 Here they are, each one an individual mason bee in a cocoon. When you buy your "starter bees" at a garden store or in my case the Backyard Bird Shop, you get a small box with a few of these in it. December through about March is the time to buy them. You then place the box in the refrigerator until March, take it out, tape it to the top of your sparkly clean and EMPTY mason bee house fresh with clean tubes and that's it. They chew their way out of the cardboard box and find the tubes or holes (like magic!) and start pollinating and making new mason bee babies right away.

 Closeup cam! Still some bee poop but apparently that's ok. I hope I did right by our bees!

 So what to do with them next? I let them thoroughly dry on a towel, then found a cardboard box to put them in. I removed this towel, it did not get stored with the bees.

My cardboard box has a couple of these slots for air. I will now find a metal box (from a tin of cookies or something like that) and put this box inside of it for extra protection. The whole thing lives outside (it could live in the fridge but it's too big). Crown Bee's website says the fridge is good but new frost-free refrigerators are not humid enough, but they carry special humidity chambers you can buy to solve this issue. I am choosing to leave them outside just as they are in nature, and many websites I have found say that's the best way to go, just don't forget about them if they are still in a tin box when spring rolls around.  My bees live in my garden shed which is unheated (they need the cold) but shelter from rain and predators.

So that's it, when spring does roll around again, I will take the cardboard box out of the metal tin and place it within the vicinity of my now super squeaky clean mason bee nests with brand new liners and tubes. 

This is our original mason bee block. It works except that you can't clean it and the birds found a new food source,  hence the wire. I don't know if any of these guys will make it or if any are even left inside those holes, but we'll see. When it's spring I'll take this box off of its mount and put it in a closed paper bag with a small hole in the bag for emerging bees to get out. In theory, they won't fly back into the closed up bag so after a time, the bee block will be vacant. Then I can re-drill the holes to give it a good cleaning. Just a different way of going about it than with the tubes, it still works just fine if you're not interested in cleaning it out. A lot of people toss theirs when they are vacant after a year or two and just buy or make new ones. Making them is pretty straightforward.

Why the heck is my skeleton in this post? Here's a funny observation. Well, the "rib" parts of it is made of bamboo and are hollow. Hmmm...just perfect mason bee size. Yes, they found homes in those, too. Each of those three "ribs" are filled with cocoons. I cannot do anything to clean it out, so I'll leave them to their devices. I love nature!

If you do decide to host mason bees, whichever way you go (tubes with liners or a drilled block), it's up to you and fine. The "au natural" approach is just fine too, because, after all, that's what they do in nature. They find cavities (or skeletons) to make nests in nature and no one cleans those out. The advantage to cleaning is that you greatly reduce the risk of diseases and mites, plus you don't lose as many as I did. 

Now's the time of year to clean and harvest your mason bees nests, from Halloween through December is what I understand. If you've had experience with all of this, please leave a comment as I'm new at it and certainly learning and would love to hear about others' experiences. If anything, I hope I've inspired you to add a couple of mason bee blocks or nests to your garden - if I can handle the worst part of it, the cleaning, then you can too. There are many places I could have gone to participate in a "cleaning/harvesting party" with other bee keepers and it probably would have been very helpful. But I'm a loner, a rebel. Plus I was embarrassed by the mold.

OK, that's it from Chickadee Gardens this week. 
Thank you for reading and until next week, happy (bee harvesting) gardening!


  1. I really appreciate you sharing your newbie experience with cleaning the mason bee houses and cocoons. What did you wash your houses with? Soap and water? Just water? I've been wanting to do mason bees for a few years now. Maybe this spring will be my time to just do it.

    1. Definitely give it a try, it couldn't be easier and there are lots of resources to help if you have questions. I cleaned the houses with soap and water and a good scrubbing. That's it, I didn't want to introduce any chemicals at all. I think since they dried completely it will be enough - in other words I was just trying to prevent mold from growing. Do it, Alison !! :) It's a lot of fun. If you are down this way any time soon I'll give you some cocoons.

  2. Fascinating! You said they need exposure to cold - are there temperature guidelines? We don't freeze in my area of southern California (which also affects/limits the fruit trees we can grow).

    1. Hi Kris…I see I replied in the wrong place…see below!

  3. Hi Kris, it seems as though the fridge might be the way to go - I have found this website to have some answers -

    Hope this helps, I think you could be very successful at this in southern CA. You can also contact Crown Bees (in Seattle area) - they are VERY knowledgable and helpful.

  4. Interesting…I had no idea ! Chickens and Mason bees ? I'll have to do some serious research .

    1. Yes, all I need are chickens now and I'll have the farm I always dreamed about... :) Love 'em both.

  5. This was such an informative post! I wonder if we have some similar bees here. So sweet that they made homes in the skeleton.

    1. Hi Amy! Well, it's not one of those pretty posts with lots of great foliage shots...but thanks for reading! I do wonder if you have some such bees in Australia...I bet you do have something, it would be interesting to find out as your flora and fauna is so unique. As for the skeleton - I think I have a year-round Halloween ornament!

  6. Ohhh this is great!!! I didn´t know you could do something like that...I love it. Thanks for the information!!!

    1. You bet, Lisa - thanks for reading! We have to do all we can to promote pollinators in this world so it's my little bit.

    2. Anonymous12:00 AM PST has lots of info. Enjoyed your beginning experience with the bees. Sondra

    3. Thanks, Sondra! I love the experience, it's fun to learn and really, pretty straight forward. Thanks for reading and for commenting.

  7. Hello - thanks for your photos/essay. I am wondering what you washed the cocoons with. Some folks use diluted bleach water. Thanks for commenting. I wish you renewed success this spring!

    1. Hi Brian - thanks for commenting and reading! I just washed the cocoons with cool water, I suppose you could use bleach although I am not sure about that…you might want to ask Crown Bees, they are a great information source. Thank you for your kind wishes, I wish you the same!

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