Solitary Bees
Harvesting and Storing Mason Bee Cocoons
Mason Bee Nesting Tube Anatomy
In the back of a nesting tube, a female mason bee will make a little pollen and nectar loaf. Then she will lay one egg on top of the loaf and seal off the chamber with a layer of mud, repeating this process along the length of the nesting tube. One tube can usually fit five to eight egg cells. She tends to lay females toward the back of the nesting tube and males toward the front since males emerge earlier. She will then leave an empty chamber (without pollen or an egg) and close it with an extra thick mud cap on the end.
Intact Summer Storage
Mason bees only live 4-6 weeks. Around mid-June, your bees should be done laying and you can remove nesting materials from your bee house. Individual cardboard tubes or reeds can be removed as they’re filled, but do this at night so the remaining active bees can reorient in the morning. Wait to remove wooden trays until all females are done nesting. Store the nesting tubes in a fine-mesh bag (to protect from tiny predators) and store the mud-capped end facing up (so the larvae sit on their pollen loaves). Don’t open any nesting tubes or disassemble any wooden trays. The mason bee is in its larval stage and needs to remain within its little chamber throughout the summer. You want to make sure your bees have the heat they need to develop, so store the nesting materials within the fine-mesh bag in an unconditioned shed or garage. If your shed or garage is warmer than outdoor temperatures, find a cooler place to store.
Harvesting Mason Bee Cocoons
Harvesting cocoons helps keep your mason bees healthy and also allows you to take inventory. This is best done between October and December.
Make a gauge stick to check for partially filled tubes. Take a bamboo skewer and mark it at the length of the nesting tube. Gently insert into your tubes that don’t have a mud cap on the end. If the mark protrudes out of the tube, there is at least one nesting chamber inside. If it doesn’t protrude, the nesting hole is empty. Set it aside and use it next spring.
For cardboard tubes, just tear or snip and unravel.
For reeds, pinch the mud-capped end between your fingers and the reed will start to split or carefully split the mud-capped end with a blunt butter knife. Since there is an empty chamber at the open end of the reed, you don’t have to worry about accidentally harming a cocoon. Pry the reed apart and gently remove cocoons with a flat-head screwdriver held at a 45 degree angle. Catch cocoons in an empty tub or on newspaper.
For wooden trays, remove the rubber bands and any cardboard backing. Lift the first tray and gently remove cocoons with a flat-head screwdriver held at a 45 degree angle. Catch cocoons in an empty tub or on newspaper. Make sure to check both the top and bottom of each tray. Brush away debris with a stiff brush or toothbrush. If you see chalkbrood, you can dip an old toothbrush in a mixture of water and bleach and scrub. Allow to dry and then reassemble before storage.
Making a gauge stick and harvesting from reeds.
Harvesting from wooden trays.
Cleaning Mason Bee Cocoons
Mason bee cocoons are tough and waterproof for up to 30 minutes. After harvesting your cocoons, separate them from other nesting debris by hand. Add lukewarm water to a bowl and stir or rub the mason bee cocoons. Allow to dry for 30 minutes, then place inside your container in the refrigerator.
If you see signs of chalkbrood, add 1 tablespoon of bleach to 1 cup of water. Rinse with clean water before drying.
You could also skip the water and gently scrub the cocoons in your hand with some fine sand to remove debris.
Storing Mason Bee Cocoons
Store mason bee cocoons in a plastic container or paper bag in the refrigerator (34-38°F). This helps the mason bees conserve their energy stores. Check monthly for signs of mold and clean the cocoons if present.
That's it until next spring!
No further steps are required before next spring when it’s over 55°F and time to pollinate!