How to protect my mason bee house from parasites
So I built a mason bee house which has been successfully running for few years. During the summer, after bees stopped all the activities, I regularly check and clean the cells. I don't touch the closed cells. But I take the other cells left empty, I clean them and I store them ready to be placed back in the house at the beginning of the next spring.
Last summer, while cleaning the empty cells I found some six spotter spider beetles. I understood those are parasites for the bees and I want to avoid as much as possible to found those bug again.
Is the cleaning process ok, or should I improve it? Is there any mean to repel or avoid these parasites to get back?
Location: hills in the northern Italy
Other Info: bee house is a self made wooden box, filled with bamboo sections left naturally closed on the back side.
Thank you!!