Homebuggarden commented earlier this week:
“Has anyone come across a good source of information on providing nest support for alternative pollinators such as bumblebees, digger bees, and the like?”
There is Michigan specific advice in a PDF here (and any day now I’ll get around to reviewing the awesome paper those authors published in Ecology Frontiers….) There is also a plant list for Michigan in this PDF publication.
You can find a list of all the excellent Xerces Society publications online here, downloadable free as PDFs!