Asked January 13, 2021, 9:52 AM EST
Franklin County Ohio
Hi Mason Bee supporter! I have looked at several sources about Mason Bees and their culture. The pupae are right now inside the tubes of the bee shelter. They will emerge this spring and start the pollinating/egg laying season once again. To do something to the tubes with the pupae inside would not be a good thing in my mind.
I'm going to attach a file from extension in Wisconsin that tells about the bees. They suggest getting a new nest box or making your own nesting box using hollow tubes plugged on one end.
They also encourage the use of an emergence chamber which is a box or dark bucket with a lid with a hole drilled into it. Put the bee house inside there and let them emerge this spring and migrate to the new shelter that you have put up. That would be the best way to not harm the bees and not let them reuse the old nest which might or might not have parasites in there.
I would always like to have nature take its course with wild things. The solitary bees that emerge will be the strong ones and start a new nest in a clean nest box.
PS: If you make your own nest box, cut the tubes 6 - 8 inches as that is the optimum. The longer the tubes, the better chance of female bees emerging. Don