cross-posted from: https://slrpnk.net/post/37788207
https://www.torreyaguardians.org/pawpaw-ecological-michigan.html
The title says it all, but most of sap beetles life cycle happens in a small area because they're weak flyers. They need leaf litter to reproduce and larval beetles live off the rotting fruit.
You guys have Cherry Orchards in the PNW. There's probably some that have been introduced to your area.
While I strongly advise against importing them, you could probably go to a u-pick cherry orchard and grab some rotten cherries off the ground. And place them under your pawpaw trees and see how that goes next year.