In early May I conservatively estimated we would end up with about 250 cocoons by the end of the season. As it turns out, this was a really good year for Mason bees. After sorting and cleaning, we have 430 cocoons – a 6-fold increase from our starting numbers. Generally a 3-fold increase is considered good, so this is exceptional. I’ll be able to distribute some mason bees to our various garden patches, and still have plenty left over to share with other folks interested in getting started with mason bees.
I did notice a few cases of chalkbrood. Not wanting to take any chances, I put all the cocoons through a 5% bleach wash. They feel so brittle and fragile, but these cocoons are evolved to survive a winter outdoors and are surprisingly tough. For good measure I also sprayed the mason bee blocks with a 10% bleach solution.
Now we just have to make sure they overwinter well. A cool, dark, dry spot is best. I keep them in a box that I put inside a mesh bag, to protect it from rodents.