How to Wash and Store Mason Bee Cocoons

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Being the better pollinator in comparison to honeybees has made mason beekeeping useful and popular. For best results with your mason beekeeping, here is a guide on how to wash and store mason bee cocoons. The guide covers the process of harvesting cocoons, cleaning them up, and storing them in the best way to ensure you get healthy mason bees from the cocoons.

Poor harvesting, cleaning and storage techniques kill mason bees in their cocoons. It is important to wash mason bee cocoons for various reasons including disease and pest control. Equally important in storage in the right conditions so that mason bee cocoons remain viable. Handle mason bee cocoons with care when harvesting, washing and storing them. They contain living organisms in them that you do not want to hurt.

For more information on washing and storing mason bee cocoons, be sure to check out Crown Bees, a highly reputed company specializing in mason and wild bees in the United States.

Mason Bee Life Cycle

Wash and Store Mason Bee Cocoons - Mason Bee Life Cycle

Mason bees have a lifecycle that includes a pupa stage which then transitions into an adult, as is typical with insects. The pupa stage starts when mature larvae make a cocoon around themselves. Usually, the main material used to make the cocoon is silk. It is the pupa stage that needs the cocoon for its development. The adult stage eats or tears its way out of the cocoon. Harvesting mason bee cocoons allows you to provide security for the cocoons away from the natural environment where the predators would eat the developing pupa or trapped adult mason bee.

Mason bees build nests in tubes that are natural or provided by mason beekeepers. Accessing cocoons is therefore necessary for purposes of propagating new mason bee populations as well as ensuring better survival of the mason bees. Harvesting the cocoons requires opening up the nesting material in which the mason bees have built their nest. The methods and tools used in harvesting cocoons vary by availability and by the type of nesting material you are working on. Use a hand lens to inspect your mason bee cocoons after harvesting them.

How to Harvest Mason Bee Cocoons

To harvest mason bee cocoons, take apart your nesting material. This may involve cutting, splitting or disassembly. You may also tear apart some nesting tubes such as those made using cardboard. In some instances, mason beekeepers use inserts in nesting tubes. Pull out the insert if you used it in your mason bee nesting tubes and tear it carefully to access cocoons. Wooden trays need you to take them apart to access the cocoons. Nesting reeds require splitting apart so you can reach the cocoons. Mason bees use mud to seal in individual cocoons. Do not be worried when you find some mud in the nesting tubes or inserts you use for mason beekeeping.

In harvesting mason bee cocoons, take care not to damage them. Use tools that are not too sharp, and be careful in the entire process. Piercing or cutting the cocoons can hurt the adult mason bees inside. After harvesting the cocoons from mason bee nesting tubes, agitate them lightly in your hand to remove any mud caked on them.

Benefits of Harvesting Mason Bee Cocoons

Wash and Store Mason Bee Cocoons

In the wild, mason bees have many predators, pests and diseases that affect or are transmitted through mason bee cocoons. Harvesting cocoons requires you to then wash and store mason bee cocoons for best results. It gives you an opportunity to address the challenge of predators, pests and diseases in mason bees. Additionally, harvesting gives you an opportunity to clean nesting materials for subsequent use. This is only applicable where you use reusable nesting materials with your mason bees.

Harvest mason bee cocoons in late autumn. This allows the mason bees to have developed fully and ready for winter hibernation. Typically, mason bees develop in autumn and then overwinter through the winter season to emerge from cocoons in spring. Harvesting the cocoons earlier and storing them away may interrupt the development process of mason bees that have not finished the lifecycle process until adult stage. You will therefore have delayed escape of the bees from cocoons after putting them in mason bee habitats in spring.

How to Identify Healthy Mason Bee Cocoons

Mason bee cocoons are gray-brown in color. They may be covered with some small dark-colored frass pellets of the larva’s excrement. Healthy cocoons are oval-like in shape. They are full, sealed and not crunchy. The healthy mason bee cocoon floats in fresh water and is water-repellent. It is firm to the touch.

Unhealthy, damaged or infected cocoons sink in fresh water and are dimpled like a raisin. They may be open and feel crunchy in your hand. Light color is also an indicator of cocoons that might have problems.

Inspect cocoons in a dark room by placing them on a clear surface and shining a flashlight under them. Discard those cocoons that look hollow in this inspection exercise.

Washing Mason Bee Cocoons

Washing mason bee cocoons is important for pest and disease control. It removes disease spores, pest eggs and pests themselves from the cocoons. This makes it possible to have a future generation of mason bees that are unaffected by the pests and diseases.

Mason bees have few pests that attack them. They also have few diseases that infect them. Even then, the effects of these diseases and pests can be devastating to mason bee populations. Washing mason bee cocoons removes the infectious agents of diseases and the pests from the cocoons. They cannot therefore get onto the emerging adult mason bees and cause their negative effects on the bees.

Chalkbrood is the major disease that infects mason bees. It is fungal. The main pests of mason bees are pollen mites, dermestid beetles, and parasitic wasps. Pests and diseases of mason bees affect the bees at various stages in the lifecycle including feeding on pollen and nectar that is meant for mason bee larvae and affecting developing bees.

How to Wash Mason Bee Cocoons

There are two major methods of washing mason bee cocoons. One uses bleach to chemically affect fungal spores and pests. The other is using sand to physically remove fungal spores and pests from the surface of mason bee cocoons.

Washing Mason Bee Cocoons Using Bleach

In this method, you use some bleach solution to wash the mason bee cocoons. The bleach kills fungal spores and pests chemically. To clean the cocoons using bleach, follow the following process:

  1. Place the cocoons in some water that it at room temperature. Do no use cooled water, or heated water. Water loosens dirt, mites and feces that might be stuck on the cocoons. Agitate the cocoons using your hand for up to half a minute. Debris falls to the bottom of your water container. Cocoons that sink to the bottom are spoilt, damaged or unviable.
  2. Sieve out the floating cocoons and put them in another container with bleach solution. Soak them and then scoop them out for rinsing. Do not use soap or detergents to wash mason bee cocoons.
  3. Place washed mason bee cocoons on some absorbent paper towel or cloth to dry for about 1 hour. Do not put them under direct sunlight or heating of any kind.

Bleach solution for washing mason bee cocoons requires careful preparation. The concentration of bleach in the solution determines how long you can soak them in the solution. Soaking them in the solution for extended periods of time causes the bleach to reach the developing mason bee and kill it. During soaking, agitate the cocoons lightly and gently.

  • For 5 percent (5%) solution, soak the cocoons for 5 to 15 minutes.
  • By approximation, you may prepare a bleach solution at a rate of 1 tablespoon for every cup of water. In this solution, soak the cocoons for 5 to 15 minutes.

Washing Mason Bee Cocoons Using Sand

Washing mason bee cocoons using sand removes disease spores and pests physically. It has less operator error and is easy to do. This method of cleaning mason bee cocoons is fast, effective and has little chance of damaging the mason bee cocoons. Due to the small size of fungal spores, the cocoons are not sanitized, so they may need further cleaning with bleach solution. With cocoons that have fungal spores on them, the sand you use to clean them with will infect other cocoons in future. Therefore, use the sand for only one batch of cocoons from a single nest in a season. To clean mason bee cocoons using sand, follow the process below:

  1. Place mason bee cocoons in some fine small-grained sand. You may wet the sand if you want.
  2. Agitate the sand around and mix it up gently for a few minutes. You will see the cocoons get clean until there is nothing stuck on the surface of the cocoons.
  3. Remove the cocoons from the sand and store them away.

Hybrid Method for Washing Mason Bee Cocoons

Combine the bleach and sand methods of cleaning mason bee cocoons to benefit from their advantages. In this method, you use bleach solution to wet your fine-grained sand. You allow them to stand in the sand and soak for some minutes.

  • Agitate the sand and cocoons mix for physical removal of material sticking onto the sides of the cocoons.
  • Remove the cocoons from the sand once they are clean and soaked for long enough and rinse them using clean water.
  • Set the cocoons on a clean absorbent cloth or paper towel to dry for 1 hour.

Do not allow direct sunlight onto the mason bee cocoons. You should also not heat the cocoons to speed up drying.

Storing Mason Bee Cocoons

After your washed mason bee cocoons are dry, storing them is the next step. You will take then from storage when it is time to place them in your mason bee habitat in spring. Well-developed mason bee cocoons release adult mason bees soon after they are placed in the warm mason bee house in spring.

Storing Mason bee cocoons requires that you allow for circulation of fresh air around the cocoons. This is because cocoons contain a live mason bee in them. The bee requires oxygen for its survival. Additionally, you should control humidity in the storage environment. Check on the cocoons once in a while. A visual check is adequate. You should also ensure proper temperature and moisture control when storing mason bee cocoons.

For best results with storing mason bee cocoons, the vegetable bin of your refrigerator is great. It allows for adequate cooling of the cocoons without lowering the temperature too much. Ensure the cocoons are not squished or wet in the vegetable bin, if you use it.

Temperature Control

High storage temperatures cause the adult bee in the cocoon to finish its final development and emerge from the cocoon. Very high temperatures kill the bee in the cocoon. Cold temperatures stop development of the pupa in the mason bee cocoon. Very low temperatures kill the pupa in the cocoon. For these reasons, it is recommendable that you store mason bee cocoons at a temperature of 37-39 0F.

Humidity Control

Humidity around stored mason bee cocoons should be at 60-70%. This is adequately addressed by having a moderately wet cloth or paper towel in the same space as the mason bee cocoons. The wet item should not be dripping wet.

Inspecting Stored Mason Bee Cocoons

Inspect stored mason bee cocoons once in a while. Danger signs include wetness of the cocoons, mould growing on the cocoons and drying out of the cocoons. If you notice wetness or dryness, adjust the humidity of the storage environment. Also ensure the cocoons are not in constant contact with water.

Mold growing on stored mason bee cocoons is a sign of wet storage environment. It is adequately addressed by washing them using the bleach method and then air-drying the cocoons for about 1 hour on a paper towel or screen. Before returning them to the storage space you were using, address excessive humidity in the space.


Proper cleaning and storage of mason bee cocoons contributes to healthy mason bee populations. It ensures that your mason bees emerge healthy and their nest remains free of diseases, pests and predators.  Use the cleaning method that is most suitable for your mason bee cocoons based on their state when you harvest them. Conventionally, you can use sand or bleach to clean the cocoons. The hybrid method covers both possibilities of infested and non-infested cocoons. Use the tips in this guide on how to wash and store mason bee cocoons for a vibrant mason bee population. Follow them accurately to get the best out of your mason beekeeping operation.

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About Michael Simmonds

Michael Simmonds is an American beekeeper with more than two decades of experience in beekeeping. His journey with bees began in his youth, sparking a lifelong passion that led him to start his own apiary at the tender age of 15. Throughout the years, Simmonds has refined his beekeeping skills and has accumulated a wealth of knowledge concerning honeybee biology and behavior. Simmonds' early exposure to beekeeping ignited a fascination with these pollinators, influencing his decision to establish BeeKeepClub in 2016. The website was created with the aim to serve as the ultimate resource for beginners interested in beekeeping. Under Simmonds' guidance, BeeKeepClub provides comprehensive information to novices, including the basics of beekeeping, the different types of bees and hives, the selection of hive locations, and the necessary beekeeping equipment. In addition, the site offers detailed reviews of beekeeping tools to help enthusiasts make informed decisions and get the best value for their investment​​. His contributions to the beekeeping community through BeeKeepClub are substantial, offering both educational content and practical advice. The website covers a wide array of topics, from starting an apiary to harvesting honey, all reflecting Simmonds' extensive experience and passion for the field. Simmonds’ approach is hands-on and educational, focusing on the importance of understanding bees and the environment in which they thrive. His work not only guides beginners through their beekeeping journey but also reflects a commitment to the well-being of bees. Michael Simmonds has dedicated a significant part of his life to bees and beekeeping, and through BeeKeepClub, he has made this knowledge accessible to a broader audience. His work undoubtedly embodies a blend of expertise, authority, and trustworthiness in the realm of beekeeping.
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Annette Barsby
Annette Barsby
2 years ago

I’m so glad I found this article. It helps the back yard beekeepers amongst us, to clean efficiently our cocoons for storing in Winter. Most I have come across are designed for commercial solitary bee keepers. Now I feel more confident I can carry out the procedure to best protect my bees to come. Thank you

Dave Natkiel
Dave Natkiel
2 years ago

Very interesting and helpful

1 year ago

I’m a newbie, just gathering info to get started with Mason bees. I live in a high desert region where temps don’t fall below freezing, but get into the low 40s at night during December and January, 60-70 daytime. By March, daytime temps can reach 70-80, nights still cool 50s. It gradually begins to heat up during April and May is hot and dry, with daytime temps in the 90s and nights in the 70s. June, rainy season begins and both day and night temps are moderate through August, cooling fairly gradually until December. Given these temperature ranges and times,I… Read more »

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