7. How to Harvest Bee Cocoons


7.2 Harvest Spring Mason Bee Cocoons

7.2 Harvest Spring Mason Bee Cocoons

Spring mason bees hibernate as fully formed adult bees inside of waterproof cocoons.

Harvesting mason bee cocoons is easy, quick, and allows you to:

  • Remove healthy mason bee cocoons from pests & diseases.
  • Take inventory of your mason bee population.
  • Share extra mason bee cocoons with local friends and neighbors.
  • Participate in Crown Bees nationwide BeeBuyBack program.
    • BeeBuyBack: Exchange your extra mason bee cocoons for a Crown Bees gift card or check, your mason bee cocoons will be shared with gardeners and farmers across the country.

We know this can be a little intimidating for first-timers, so we've created a simple guide with video tutorials to help you along the way. You'll learn the importance of harvesting cocoons, the best harvesting practices for our three different types of nesting materials (natural reeds, wood trays, and cardboard tubes), and how to clean and store your mason bee cocoons for healthy spring bees!

Harvesting Steps:

  1. Open nesting materials and remove healthy cocoons.
  2. Wash cocoons, treating with CleanBee if chalkbrood is found.
  3. Store clean cocoons in your fridge in a HumidiBee container.

When to harvest: Start in October until December.

Tools you need: scissors, a stiff wire brush or old toothbrush, paper towels, bowls and a colander or strainer for washing mason bee cocoons, bleach or CleanBee in case of chalkbrood, a HumidiBee for storing clean cocoons, and a Cocoon Comb for removing cocoons.

Set up a workspace: A cool room to help keep the mason bee cocoons in hibernation (try opening a window) and newspaper or a pan for catching cocoons and debris.

Gauge Stick: Check to see if your Natural Reeds or BeeTubes have been partially filled by making a gauge stick. Mark the stick at the length of the nesting tube and place the gauge into the nesting hole. If the mark protrudes, there is a nesting chamber inside. If not, the nesting hole is empty and you can set it aside for use next spring.

Pro Tip: Easily check for mason bee mud at the spin-closed back end of our cardboard BeeTubes.

What You’ll See:

  • Healthy mason bee cocoons
  • Mud walls and mud capped ends
  • Mason bee frass (small black specks)
  • Houdini Fly
  • Chalkbrood
  • Pollen mites
  • Pollen loaves - the bee egg didn’t hatch
  • Meal moths (adults and caterpillars)
  • Dead mason bee larvae
  • Mason bee cocoons with small holes (mono)

If you find large, chubby, or plump larvae that completely fill the nesting chamber or non-mason bee cocoons, these may be a wild bee or beneficial wasp. If you can, close the nesting hole and store overwinter in the BeeGuard Bag in your unheated garage or shed. If you must remove wild bee larvae, store them overwinter in a smaller CocoonGuard Bag.

How to Open Spring Mason Bee Nesting Materials (8mm)

Wood Trays

  1. Remove the green rubber bands and the cardboard backing (save both to reassemble the trays).
  2. Lift up the first tray and using the Cocoon Comb, gently remove cocoons and mud walls. Keep your removal tool at a 45-degree angle.
  3. Check both sides of the nesting trays for cocoons.
  4. Brush away any pollen mites and mason bee frass with a stiff brush.
  5. If you found chalkbrood, spot clean with an old toothbrush dipped in a bleach and water solution. Or lightly apply Clean Bee spray, a safe alternative to bleach, and use a dry brush to bring Clean Bee into the wood grooves.
  6. Reassemble nesting trays by aligning the side notches, ensuring that the nesting holes are snug and there are no gaps.
  7. Store over winter with cardboard backing and rubber bands attached to trays.

For a more detailed tutorial on harvesting wood trays, check out our 2020 Livestream!


Natural Reeds

  1. Pinch the mud-capped end between your fingers and the reed will start to split. Don’t worry, there is no cocoon at the open end of the reed.
  2. Pry the reed apart along the split and use a Cocoon Comb to gently remove cocoons.

For a more detailed tutorial on harvesting natural reeds, check out our 2020 Livestream!


Cardboard BeeTubes with Inserts

Remove the Easy-Tear Insert from the cardboard BeeTube and choose an option below.

Option 1: Got lots of Inserts? Soak the Inserts in a warm water solution to loosen the glue. Do not soak the Inserts longer than 30 minutes.

Option 2: Tear or snip one end of the Insert and it will easily unravel. Use your fingers to gently separate mason bee cocoons from the Insert.

For a more detailed tutorial on harvesting cardboard tubes, check out our 2020 Livestream!


Cardboard BeeTubes

  1. Tear or snip one end of the BeeTube and unravel along the spiral.
  2. If a cocoon is stuck at the back end, gently push it out from the spin-closed end using an opened paperclip.

How to Wash Spring Mason Bee Cocoons

Mason bee cocoons are waterproof and can withstand about 30 minutes of soaking, but less time is always safer. Add lukewarm water to a bowl and stir or rub the mason bee cocoons, frass may need some friction to be removed from the outside of the cocoon.

    • If you found chalkbrood: add 1 Tbl of bleach to 1 cup of water and gently stir. For larger batches of cocoons add 1 cup of bleach to 1 gallon of water. Rinse cocoons in fresh water to remove bleach solution.
      • Pro Tip: Clean Bee is a safer alternative to bleach for removing chalkbrood spores. Spray Clean Bee on both sides of dry mason bee cocoons.
    • Pat mason bee cocoons dry and allow to dry for 30 minutes.
    • Place clean mason bee cocoons into your HumidiBee container and store the cocoons in the fridge overwinter, see below.

Winter Mason Bee Cocoon Storage

Mason bee cocoons are waterproof and can be washed and stored over the winter in your fridge. The consistent cold temperatures of your fridge help the mason bees conserve their fat over the winter. We recommend setting your fridge temperature to between 34F-38F (1-3C). To prevent dehydration of mason bee cocoons, Crown Bees has developed the HumidiBee cocoon humidifier that retains moisture in today’s frost-free refrigerators.

Add about a tablespoon of water once a month to your filled HumidiBee container and wash moldy cocoons and spray with Clean Bee as needed. Mason bee cocoons can become moldy in the fridge and the source of mold is from cheese or other food. If mold is a persistent problem, place the HumidiBee container into a paper bag and close the top. Mold spores may have a harder time penetrating the paper bag.

    • Sign up for BeeMail to receive monthly hydration reminders and tips for success.

Take Inventory and Share Mason Bee Cocoons

We care about your mason bee-raising success and hope you will have more mason bee cocoons than you need. Here are a couple of easy guidelines to help you know how many mason bee cocoons to keep:

    • Keep a little more than 1 mason bee cocoon per nesting hole.
    • Keep a minimum of 10 mason bee cocoons per mature fruit tree.

For example, to maintain a 48-hole wood tray for mason bees, keep about 50-75 mason bee cocoons. Keeping a little extra will ensure that you have enough healthy adult bees emerge next spring.

Every yard is different and with experience, you will get to know how many mason bee cocoons your garden, orchard, or forest can support. Many of our customers like to keep about 200 mason bee cocoons to raise in their backyard. You may need to increase your number of nesting holes or add an extra mason bee house to the other side of your garden.

You can either share your extra mason bee cocoons with local friends and family or participate in our BeeBuyBack program and help us meet the need of 1 billion mason bees for farms across the country.

Topic Completion

How to Harvest Bee Cocoons

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