Do Mason Bee Houses Need Cleaning and Winter Storage

What is the recommended schedule for harvesting and cleaning mason bee cocoons?

The best time to harvest and clean cocoons is late autumn, specifically after the bees have entered full diapause. Aim to finish this work once nighttime temperatures consistently drop below freezing, typically in November. Many people assume that leaving the nesting materials undisturbed mimics natural conditions and is therefore safer for the bees, but this practice actually allows parasites to thrive unchecked. By removing cocoons from the nesting tubes, you disrupt the life cycle of pests that would otherwise overwinter in the same structure, ensuring a significantly higher survival rate for the next generation.

How should cocoons be sanitized to prevent the spread of chalkbrood and other diseases?

Yes, you should submerge cocoons in a mild solution of 1 part bleach to 100 parts water for no more than 2 minutes. This brief rinse effectively kills fungal spores like chalkbrood without harming the developing bee. Always rinse them thoroughly with fresh water afterward to remove any chemical residue.

How can predators like parasitic wasps or pollen mites be managed during the cleaning process?

Managing pests requires a two-step approach: physical removal and environmental control. During the harvest, use a soft-bristled brush to gently remove loose debris and mites from the surface of each cocoon. If you encounter cocoons covered in a fine, orange dust, these are likely infested with pollen mites and should be separated from healthy ones immediately.

The exception to this manual cleaning involves cocoons that appear damaged or have holes, as these often contain parasitic wasp larvae. Do not attempt to clean these; instead, destroy them to prevent the wasps from emerging in your storage area. While some practitioners recommend using a mild soap solution for washing, simply rinsing with cool water is usually sufficient if you are diligent about removing visible debris during the initial inspection.

What materials are most effective for replacing nesting tubes after the cleaning cycle?

The most effective nesting materials are those that allow for easy opening and annual replacement, such as natural reeds or heavy-duty cardboard tubes.

• Natural reeds: These provide a varied diameter, which mimics the diverse nesting holes bees select in the wild.
• Cardboard tubes: These are designed to be pulled apart, making the annual harvest process much faster and less damaging to the cocoons.
• Wood blocks: These should feature removable paper inserts, as solid wood blocks are nearly impossible to sanitize properly between seasons.
• Paper liners: These inserts prevent the bees from cementing their cocoons directly to the nesting material, which keeps the cocoons clean and intact.

How do you distinguish between healthy cocoons and those that are non-viable or parasitized?

Distinguishing between viable and non-viable cocoons requires a careful visual and tactile examination of their physical condition.

1. Firmness: Gently squeeze the cocoon; a healthy one feels firm and resilient, while a dead or parasitized one often feels hollow or crushes easily.
2. Color: Look for a dark, chocolate-brown color, as pale or translucent cocoons often indicate the bee failed to complete its development.
3. Weight: A viable cocoon should feel slightly heavy for its size, whereas a light, rattling cocoon usually contains only dead tissue.
4. Surface: Check for small, perfectly round holes, which are clear evidence that a parasitic wasp has already emerged from that cell.
5. Shape: Discard any cocoons that are severely misshapen or covered in a sticky, wet residue, as these are likely infected with bacterial rot.

What is the proper procedure for releasing bees in the spring once they have been stored?

Wait to release your bees until the local spring bloom is well underway and daytime temperatures reach at least 55°F for several consecutive days. Place the cocoons in a release box near the nesting site, ensuring the box is shielded from direct rain and wind. The bees will emerge naturally as the warmth penetrates the cocoons, typically over a period of 1 to 3 weeks.

One important nuance is that you should never force a bee to emerge by warming the cocoons prematurely. If you release them before the flowers have opened, the bees will starve because their primary food source is unavailable. An exception exists if you are managing a large population; in that case, you can stagger the release by keeping a portion of the cocoons in the refrigerator for an extra week to extend the pollination window.