Hi Thomas,

Here are some  good articles with lots of useful information.

https://extension.psu.edu/japanese-beetles-in-the-home-garden

https://ask2.extension.org/kb/faq.php?id=317449#:~:text=The%20active%20ingredient%20in%20Scotts,killing%20pesticides%20should%20be%20applied.

Which treatment is more effective ? It would appear that the chemical might be. The bigger issue is that the beetles will still be in all your neighboring yards so they will just fly over and lay their eggs in your lawn again. The best way to deter them is by not having a lot of lawn . I suggest creating borders with shrubs, small trees and perennials and native grasses while shrinking your lawn. They are also less likely to damage lawns with other plants such as clover. If you want to plant grass you should do it now. If you wait until June it probably will be very hot and dry and hard to get growing. Another link:

https://ask2.extension.org/kb/faq.php?id=317449#:~:text=The%20active%20ingredient%20in%20Scotts,killing%20pesticides%20should%20be%20applied.

Antidotally, I notice a striking difference from the areas of my yard where I watered ( lots of grubs) compared to areas I did not water ( no grubs).  I like watching the birds that my shrubs and flowers attract.

Hope this helps,

Sally Granath

St. Louis County MG