Just need to vent...

Thank you guys for mentioning the traps. You all are 100% correct and for certain situations they are effective.
For home use they aren't effective

Should You Use Japanese Beetle Traps? Here’s What Experts Say (bhg.com)
“However, [the traps] can be a problem if you’re living in a residential area surrounded by neighbors with gardens and yards,” Smith says. “Studies show that Japanese beetle traps can lure these insects that are as far away as five miles. So, with the use of Japanese beetle traps, you might be bringing more of these pests into your backyard.”

This is what I experienced in our area. I have a mini orchard, garden, multiple berry plants in a somewhat residential setting and the traps pull in beetles to our yard from all neighboring areas - not desirable. We are one of the few people who don't have a lawn/chemical company service their yard and a natural lawn coupled with an organic garden, mini orchard and berry plantings make our yard a haven for pollinators , songbirds etc - and unfortunately Japanese beetles. I don't want to lure any more of these undesirable critters into our yards ecosystem with the traps. Even birds despise the Japanese Beetles and won't feed on them

 

I knew you didn't want the traps near the plants to protect.

 

You need to pay attention to what is up and downwind with the pheromone traps.

I put a carefully-timed dose of grub killer in the lawn about 7 years ago, followed by a few years of earthworm transplantation. I released a couple thousand european nightcrawlers into the soil to sort of take over the activity the grubs had been doing, but with better compatibility.

That worked great. No beetles, excellent soil health since.

Unfortunately the pest that hit us worst was the emerald ash borer. I've spent about $4k cleaning up after them since we got this house.

 

Killing the grubs while still in the soil is a great solution and one we use- but have a different method.

I am committed to organic measures as much as possible. Unfortunately grub killers kill much more that grubs. It sounds as if you already knew this by adding earthworms to replace the collateral carnage after using the grub killers.

I use beneficial nematodes to attack the Japanese beetle grubs

Nematodes for Grubs – When and How to Apply - LawnsBesty
Heterorhabditis bacteriophora (Hb) nematodes are the most effective against Japanese beetles, European chafers, and other grubs found in lawns. These cruiser nematodes burrow deep down in the soil as they hunt for pests. They also easily get into the body of the pest thus known for faster elimination of grubs.

Amazon.com : Bug Sales 50 Million Live Beneficial Nematodes - HB (Heterohabditis bacteriophora) : Patio, Lawn & Garden

In our area the humid southeast Japanese beetles thrive and have many other host yards than ours - because of our natural lawn, natural flower landscaping, organic garden, fruit tress etc our yard is a natural attractant and food source for these undesirable pests. When Japanese beetles find a food source, they don't keep it to themselves they send out scents/pheromones to let all their buddies know dinner is served.

 

We used the BTG stuff. It costs more, but it's just a protein derived from bacterium. No industrial pesticides or anything. Doesn't kill much more than grubs.

The downside of it is that you need to be a calendar ninja to apply it at exactly the right moment for your bugs in your soil. It will only work during a very tight window per year. I managed to nail it and have not had any need to repeat those measures.

It's harder to find than all the pesticide-based ones- those all say "season-long" because that's the selling point- you can use most any time.

 

Understand what you are saying about time sensitive - nematodes work best in early spring or sept - oct here. Any time other than those you are probably wasting your time with an application of them.