Cleaning & Storing Mason Bee Cocoons

Cleaning & Storing Mason Bee Cocoons

By Master Gardener Ranee Webb

Getting Cocoons out of liners and laminated blocks.

Liners - can be soaked in clean water for 10-15 minutes before harvesting. Set a timer. The soaking softens the liner for easier harvest.  Gently separate the cocoons & gently brush off. Cleaning will get off the rest. Or… Tear liners open (like a tube of biscuits) and gently remove contents.
Blocks - Cocoons can be removed by using a cleaning tool (¼” dowel) that is filed or sanded to a 45-degree angle. (This helps lift the cocoon up).

Gently push cocoons out of the laminated block channels.

Keep the tool parallel to the block.  If the tool is at an angle, you will squish and even pop and destroy the bee in the cocoon.  If the dried mud is very hard spray with some water to soften the mud.    

Note: Prevent warping- clean in bleach-detergent solution & clamp blocks back together.

Gently separate the cocoons & gently brush off. Cleaning will get off the rest.  


Wash and Clean Cocoons

Bleach kills chalkbrood fungus.  Dish detergent kills the mites.
Not recommended: Sand washing - does not kill chalkbrood.

1. Wearing gloves- prepare water with bleach and an unscented dish detergent (such as Dawn).
- Add 1 - 2 drops of any unscented dish detergent to one Gallon of COLD water or to one Quart of COLD water.
- Add to 2 oz. (4 Tblsp.) Bleach to one Gallon of COLD water or 1 Tbsps. Bleach per Quart of COLD water
2. Add cocoons - 2 minutes.  No longer.  Use a timer.
Bleach dissolves part of the outer silk cocoon and kills chalkbrood.
- Detergent breaks the surface tension and mites drown.
3. Swirl cocoons around. You can very gently-lightly remove some of the frass, mud, and brown and yellow residue.
4. Take cocoons out of the bleach-detergent water after 2 minutes.

5.  RINSE TWICE in COLD water to remove Bleach and Detergent.

-Use fresh water and a gentle cold stream of water
-A strainer of some sort can help contain the cocoons while rinsing.

Drying Cocoons - Put the cocoons on a dry paper towel – wait a few minutes- then transfer to a 2nd dry towel for better drying.  Let the cocoons air dry for about 1 hour.  
Do not use hair dryers or other sources of heat.

Storing Cocoons Over the Winter

Once you have harvested your cocoons, you will need to store them until it’s time for the bees to hatch.  Store them in the vegetable drawer of your fridge from October until March.

1. Put a damp (not dripping wet) paper towel in a small container.  
2. Put the small container in the larger container
3. Put cocoons on the dry paper towel in the larger container.
4. Cover larger container- lid should have a few small air holes.

The containers should be checked periodically.  

If paper towel in small container is dry, add a fresh damp (not sopping wet) paper towel.  Note: Most refrigerators are frost free.  The vegetable bin is usually more humid.  The extra dampness of the paper towel adds more humidity.
5. If there is mold, re-wash in a light bleach solution of 1/2 tsp bleach per quart     for no more than 1 minute.  Air dry again.
- Clean container with bleach- put in fresh paper towels and add cocoons.


DO NOT soak your wooden blocks and tools - prevent warping. Rinse!  
You can dry surfaces with a hairdryer on high temp after you clamp laminated blocks back together to help eliminate warping.

Putting your cocoons out in the Spring    Usually Mid-March – Mid April

  • Do you have trees, shrubs, and plants in bloom?  Watch the weather - Wait until there are several days in a row with 50-55-degree temps and no heavy rains forecast before putting out your cocoons.  
Or depend on our Bee Notes Newsletter recommendations for timing.  
  • Put a minimum of 25 cocoons out at a time. Put out ½ or 1/3 of your cocoons each time. Wait about 14 days and put out the next batch (hedging our bets on weather).  Do not fill the emergence tube more than half full.


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