Mason bees are exceptional pollinators, and properly managing their cocoons can set both you and the bees up for success in the next season. Harvesting and storing cocoons helps protect them from pests, parasites, and disease, increasing their survival rate while also contributing to the overall health of your local pollinator community.
Here’s a quick guide to seasonal mason bee management:
Why Harvest Cocoons?
Mason bee cocoons can harbour various pests, parasites, and diseases, including pollen mites, parasitic wasps, and Houdini flies. Harvesting allows you to clean the cocoons, reducing the risk of infestation and giving emerging adult mason bees a healthier start in the spring.
When to harvest cocoons?
For a deeper understanding of the mason bee lifecycle, check out our previous blog post, Mason Bees on Vancouver Island. As explained there, cocoons should be harvested around November, when the cocoons are fully spun and the larva has developed into an adult mason bee. This is the time to harvest your cocoons. Harvesting too early may disrupt their development, as they may not yet be fully formed.
How to harvest cocoons?
There are several methods for harvesting mason bee cocoons, but here’s a simple and effective approach:
Step 1: Open the Nesting Tubes or Trays
Carefully separate the tubes or open the trays to access the cocoons inside.
Step 2: Extract and Sort Cocoons
Remove the cocoons, discarding any debris. Quickly inspect them—plump, healthy cocoons should be kept, while moldy or shriveled ones should be discarded.
Step 3: Rinse the Cocoons
Place the cocoons in a strainer and rinse them with cold water. If debris is stuck to the cocoons, gently rub them between your fingers to remove it.
Note: Mason bee cocoons are waterproof and can tolerate short exposure to water, but avoid soaking them for too long (longer than ~10 minutes)
Step 4: Dry the mason bee cocoons on a paper towel. Pat dry and let them rest to air dry for a few hours.
Step 5:
Place the dried cocoons in a ventilated box and store them in your refrigerator's crisper drawer or another cool, stable environment. If storing in the fridge, make sure the drawer retains some moisture—not too dry and not too humid.
Tip: Place a damp paper towel next to the cocoon box. If it dries out quickly, re-moisten it. This prevents your cocoons from drying out.
When to Release Your Cocoons
In spring, once temperatures are consistently warm and flowers are blooming, it’s time to release your mason bees! On Vancouver Island, a great natural indicator is dandelions in bloom, this tends to occur in May! Why dandelion bloom? This tends to be our indicator that the weather is consistently 'warm' and when the mason bees hatch, they will have food!