Northern MI, growing zone 4B, residential lot with poor, sandy soil. We have been improving this in sections over time, but our entire locale is the same soil type, the preferred habitat of rose chafer beetles. If you have never encountered these, they are 1/2 inch long, narrow, olive green with brownish legs. They arrive by the thousands and mate while eating everything in their path; especially the most tender and succulent leaves (my lovely ferns) anything with white flowers (like Grandma's peonies). I hand-pick them into buckets of water, and pick, and pick - while they fly in continuously from the neighboring yards. They have no natural predators - except spiders, who are able to eat a mere handful of the ravening hoards. The birds won't touch them. They are toxic to chickens. I have tried beetle traps (white plastic jars with a rose scented lure and one-way cone shaped opening) - but I immediately discovered a honey- and bumble-bee by-catch problem with the design, so I stopped using them. We are at our wits' end. Preparing for next spring... Help?
For your own soil, a parasitic nematode could help,Steinernema carpocapsa maybe.
Another biological option is milky spore disease.
For the invader from next door, floating row covers?