Photo: How to harvest mason bee cocoons

October to December is the best time to clean mason bee nests and harvest cocoons.(Credit: Lindsay Coulter)

If you follow my investment strategy to protect nature, you'll recall that I spent 20 dollars on 20 mason bees two years ago. This weekend, I harvested over 100 cocoons (according to Dr. Margriet Dogterom, that's about 45 females and 55 males) from my mason bee house — an excellent return!

How to clean a mason bee house

Keep parasite numbers low and prevent the spread of disease within the colony by cleaning your mason bee house (and the bees!) and discarding suspicious cocoons.

Cover your work area with newspaper to collect debris like mud and bee poop. Remove all plastic or wood trays from the house. Carefully pry cocoons off and set them aside—inside are fully developed bees in hibernation. Soak trays in soapy water, scrub them with a brush, and rinse thoroughly. Soak again in a five per cent eco-friendly oxygen bleach solution to kill bacteria and fungi. Rinse well and let dry.

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How to clean mason bee cocoons

Sort your straws. Look for holes in the tube or if the mud at the entrance has been compromised. Identify suspicious cocoons with this video from Crown Bees. Unravel the tubes to separate cocoons from mud (grey), pollen (yellow), mites (red/orange) and bee poop (brown/black).
Mason Bees 036.JPG

Place cocoons in a sieve and gently rinse with tepid water. Once the water becomes clear, place cocoons in a bowl or pail of five per cent oxygen bleach solution. (Don't worry! Cocoons are buoyant and water repellent.) Soak for 5-15 minutes, stir, and then scoop the cocoons up with the sieve and rinse them well to remove all traces of bleach. Do not use soap or detergents—that will kill your bees! Place washed bees on paper towel to dry for about an hour.

Identify "suspicious" cocoons

Non-parasitized mason bee cocoons will be firm to the touch and dark-grey in colour. Keep these. Cocoons that are lighter in colour and "crispy" to the touch are likely tiny parasitic wasps. One infested cocoon can contain up to 60 developing wasps!

Bee cocoon winter storage

Mason bee colonies can be wiped out by ants, woodpeckers, squirrels, racoons, and bears. They're more likely to survive the winter if you eliminate this risk. Add clean cocoons to a paper box full of tissue or paper towel. Place the box inside a plastic yogurt container, glass jar, or metal tin—whatever will keep mice and moisture out. Punch air holes in the lid. Store your container in the fridge at 0º to 5º Celsius, in an unheated garage, or outside. Mason Bees 040.JPG

Will you clean your mason bees and their house before December? Please share any tips or advice from your experience!

Lindsay Coulter, Queen of Green

October 31, 2011

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Apr 15, 2017
1:06 PM


I have been growing my own Mason bees for a few years. I use scrap pieces of 2”×4” wood and drill numerous 5/8” holes. I place them near our fruit trees and raspberries. After each season I find that the new “homes” I put out are about 3/4 full. I store them in my shed and put them back out in late March. I don’t bother disturbing the bee larvaes. I leave them as is. Every year I give away some of these 2x4s containing the bees to friends and family. In return, I ask them to do the same.

Jan 13, 2017
7:12 AM

I just got my bee tubes in Jan. They have not been cleaned. Can I still do it or should I let them come out on their own? I live in Battle Ground WA and it has been cold here

Oct 08, 2016
9:25 PM

Hi , I am a current grad student who study Architecture at UBC. I am designing a Mason bee house for a pollenator park in Vsncourve. I have a coulpe questions. 1. Can the tube place in angle, like tilting up. The bottom is screen. 2. Will the Mason’ navigation be disrupted by the magnetic influence. Thank you.

Jul 05, 2016
7:27 AM

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Feb 02, 2016
2:43 PM

This is my first experience with mason bees, or bees of any kind. Have two hives. Bought one online with 60-80 tubes and made one copying the one I bought. Have 50-60 tubes in this one. Hoping mason bees will find the houses this spring. Will this work?


Jan 29, 2016
8:14 AM

I have cleaned the cocoons. I did not use bleach. I don’t know if there is any wasps. I have put them in a plastic container in my fridge. They are loose. Should I put tissue or paper towels in there as well? What is the purpose of the paper. Thank you, Joe

Nov 27, 2015
10:11 AM

So what do you do with the cocoons after you have harvested and cleaned them?

Oct 04, 2014
8:38 PM

I harvested my first batch of cocoons today. I’m glad I did it in early October because if I waited longer I would have lost a lot more cocoons. 1/4 of my yield was destroyed by mites, wasps or some other parasite. Some did not fully develop either. I rinsed the cocoons in tepid water and let them dry for an hour. Then I put them in a container of moist sand and rolled them around and then rinsed them again. After going through all of my cocoons, I did not see any mites or poop. They are very clean. Hopefully I’ll have a good hatching in the spring. :)

Oct 14, 2013
2:46 PM

Our Mason bee house is just a block of wood with holes drilled in it It has no wooden, paper, or cardboard straws in it. The bees have used it and we don’t want to harm any bees or cocoons. But. we would like to give them a clean house. Some holes look full and some empty so can you tell us what to do, please? Thanks

Oct 10, 2013
4:23 PM

Also..Crown Bees is doing a Share Your Bees campaign. If you have more than enough for your fruit trees and yard, we’d appreciate it if you send us your extra bees :)

See links for more info: and

Oct 10, 2013
4:00 PM

Woo Hoo! Nice post :) And thanks for linking Crown Bees in the post :)

-Hien, communications manager/social media teammate for Crown Bees

Nov 13, 2011
10:31 AM

Great article. My only criticism is the use of bleach. Bleach is kind of harsh and unforgiving. Personally I think the foundation of sustainability is respect for all living things. Why use bleach? To kill bacteria, viral diseases, and fungal organisms. The proper handling, cleaning, drying and storage of the cocoons is enough to knock back many of the diseases and disorders that affect mason bees. Leaving a toe hold for even the meanest of creatures ensures that the bees are able to express resistance and develop genetic and behavioral responses to these pressures. A little disease goes a long way to ensure healthy bee populations!

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