Your bee house may look healthy on the outside. But what’s happening inside?
Behind those mud-capped holes, pollen mites, Houdini flies, chalkbrood, mono wasps and other threats can be hidden inside the nesting chambers. If nesting material isn’t opened and cleaned each year, these threats can remain inside and spread from season to season.
Over time, your “bee hotel” can become a “predator hotel.”
Explore the predator guides to see what these threats look like inside real mason bee nests and learn how to help protect your bees.
Harvest & Clean
What's Inside Your Bee House Matters
Your mason bee house may look healthy from the outside, but you can't see what's happening behind those mud-capped nesting chambers.
Inside may be healthy mason bee cocoons, along with pollen mites, Houdini flies, chalkbrood, mono wasps and other threats that can harm developing bees and spread from season to season.
That's why opening, harvesting and cleaning your mason bee nesting material each fall is an important part of proper mason bee care.
Proper Care Starts in Spring
Fall harvesting and cleaning actually begins with the nesting material you choose in spring.
Each spring, mason bees should be given clean nesting material that can be easily opened at the end of the season, such as stacking trays or cardboard tubes with removable liners. This allows you to open each nesting chamber, inspect what happened inside, harvest the cocoons and remove predators and disease.
Harvesting and cleaning is one part of the mason bee care cycle. From putting out clean nesting material in spring to removing filled nests at the end of the season, a few simple steps can help protect your bees throughout the year.
Why Harvest & Clean?
Opening your nesting material allows you to remove predators and protect future generations of bees.
By harvesting and cleaning, you can:
Identify and remove predators and disease
Separate healthy cocoons from compromised ones
Remove pollen mites and debris from cocoons
Clean nesting material before it is used again
Help interrupt the life cycles of predators and disease
Leaving nesting material unopened year after year allows problems to remain hidden inside and continue into the next generation.
Watch How to Harvest, Wash & Store Your Mason Bee Cocoons
Not sure where to start? Watch our step-by-step video as we show you how to open your nesting material, harvest and wash your cocoons, and safely store your mason bees through winter.
Watch the Step-by-Step Video →
Watch How We Clean 3 Million Mason Bee Cocoons
Pollen Mites
Pollen mites are tiny kleptoparasites that can have a big impact on mason bees. They hide in flowers and hitch a ride on adult bees back to their nests.
Once inside a nesting chamber, pollen mites feed on the pollen loaf the female mason bee collected for her offspring. As the mites multiply by the thousands and consume the pollen, the developing bee starves and perishes, leaving the nesting chamber overrun with pollen mites.
The mites remain inside the chamber until the following spring. When mason bees emerge from nearby chambers, the mites hitch a ride on their bodies back to flowers, where they can spread to other bees and nests.
This is why opening, harvesting and cleaning mason bee nesting material each fall is so important. Removing pollen mites helps break their cycle and protect the next generation of mason bees.
Visit Our Pollen Mite Video Library
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Mason Bee Predator Research POLLEN MITES and CHALKBROOD - Study by UC Riverside
Houdini Fly
Houdini flies are invasive kleptoparasites that can quickly spread through mason bee nests. The adult fly sneaks into an open nesting chamber while the female mason bee is away and lays its eggs on the pollen loaf she has collected for her offspring. When the Houdini fly eggs hatch, the larvae consume the pollen intended for the developing mason bee. Without its food source, the developing bee starves and perishes, leaving the nesting chamber filled with Houdini fly larvae.
A single Houdini fly can lay up to 300 eggs, while a female mason bee lays only about 15 eggs in her lifetime. This reproductive advantage allows Houdini flies to multiply and spread rapidly.
If infested nesting material is left unmanaged, adult Houdini flies can emerge and continue spreading to other mason bee nests.
This is why opening, harvesting and cleaning mason bee nesting material each fall is so important. Identifying and removing Houdini flies helps break their life cycle, slow their spread and protect the next generation of mason bees.
Photo: Rent Mason Bees
We Are Hunting Houdini
If you spot houdini around your bee hotel or find their larvae inside your nesting chamber, please report it below.
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Chalkbrood
Chalkbrood is a fungal disease caused by spores that can contaminate the pollen mason bees collect from flowers. When a female mason bee gathers pollen for her offspring, she may unknowingly bring chalkbrood spores back to the nesting chamber.
When the developing larva eats contaminated pollen, the spores germinate in its gut, infect the larva and eventually kill it, leaving behind a dried, chalk-like mummy. The fungus produces more spores that remain inside the nesting chamber.
The following spring, emerging adult mason bees can crawl through these spores as they make their way out of the nest. The spores can cling to the bees and be carried to other nesting chambers and flowers, continuing the cycle of infection.
This is why opening, harvesting and cleaning mason bee nesting material each fall is so important. Removing chalkbrood and properly cleaning nesting material helps reduce the spread of fungal spores and protect the next generation of mason bees.
Visit Our Chalkbrood Video Library
What Does Chalkbrood Look Like in Mason Bees? #rentmasonbees #pollinators #garden
Summer Predator — Mono Wasp
Mono wasps are tiny parasitoid wasps that attack developing mason bees inside their cocoons. The female wasp uses her long ovipositor to penetrate the nesting material and lay her eggs inside the mason bee cocoon.
When the eggs hatch, the mono wasp larvae feed on and kill the developing mason bee inside the cocoon.
Because the damage happens inside the nest, a bee house can look perfectly healthy from the outside while mono wasps are developing inside the cocoons. If infested cocoons are left unmanaged, adult wasps emerge and can continue the cycle by attacking more developing mason bees.
This is why opening, harvesting and inspecting mason bee nesting material each fall is so important. Identifying and removing infested cocoons helps break the mono wasp life cycle and protect the next generation of mason bees.
Visit Our Mono Wasp Video Library
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Fall Harvest
Fall is harvest time! See how we harvest and clean more than 3 million mason bee cocoons each year, then learn how to do it yourself. Our step-by-step video walks you through opening your nesting materials, harvesting the cocoons, cleaning them and getting your bees ready for winter storage. Watch our harvest in action or follow along and learn to harvest your own bees.
Predator Video Library
What Predators Look Like Inside Your Mason Bee Nesting Material #rentmasonbees #masonbees
Harvesting Mason Bee Cocoons - Discover What's Inside Your Nesting Material
POLLEN MITES IN NESTING CHAMBERS AND ON MASON BEES - Learn How You Can Protect Your Bees
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How to Snip the Tip off Cocoons to Remove Mono Wasps & Help Mason Bees Emerge
HOW TO PROTECT MASON BEES FROM PREDATORS!
How We Clean 3 Million Mason Bee Cocoons to Keep Bees Healthy & Predator-Free | Rent Mason Bees
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