I would have looked into no dig gardens before you started...basically you put down sheets of cardboard on top of the grass and then add compost and food scraps/yard waste on top of that, it all decomposes into rich soil while at the same time smothering any weeds or grass....much cheaper and less time consuming than your way....those grubs are no good for plants in general..they feed on the roots of plants, alot of people I know feed them to their chickens

Here is a link that might be useful: no dig gardens

I would have looked into no dig gardens before you started...basically you put down sheets of cardboard on top of the grass and then add compost and food scraps/yard waste on top of that, it all decomposes into rich soil while at the same time smothering any weeds or grass....much cheaper and less time consuming than your way....those grubs are no good for plants in general..they feed on the roots of plants, alot of people I know feed them to their chickens

Here is a link that might be useful: no dig gardens

I would have used the no dig method but it is about 500 sq/feet and has really compacted soil. so i really wanted to break that up and use as much composted biomass as i can to save on soil cost.
Really my main concern it tilling up the soil and breaking up the compacted ground. here in Colorado its pretty much sand and clay dirt.
Its too bad it isn't a year from now i would just plant hemp and it would till it for me. but they haven't passed that bill yet.
The grass is pretty much as good as dead with the way i did it and it is breaking down now but anyway to hasten that is good so i was thinking maybe those bugs would help. but their excrement doesn't sound like it is very present for soil. looks like i will pull back the tarp and open the buffet for the local birds.

I'd also get rid of the grubs before they start laying eggs! LOL. I'm in Nevada dealing with compacted sand, so I know your difficulties. It's the only soil I've tried to dig, only to have the shovel bounce right off the top! You should have some nutrients in the clay soil, so it may be richer than you are thinking. If you have the time, you could plant cover crops, let them grow a bit, dig them under, and plant more cover crops. If you did this for a year, you'd have wonderful soil you could fork turn. I have a friend here in Nevada who did that with her compacted sand, and she now has lovely loamy soil that is workable down about 18-20 inches. She also used compost around the cover crops. Just a thought. I'm thinking about using cover crops to loosen up my soil and add organics. Best of luck to you in whatever you do!

1. You would not have sod webworms where the grass is dead.
2. Grubs are the larva of beetles and do not lay eggs.
3. The grass that was growing there is organic matter that can, and should, be incorporated into the soil while still living so it could feed the Soil Food Web.
I would remove the tarp and not use it on my soil again. The early part of June might be a bit late to seed in Alflafa, depending on where in the United States you are, always important information to include here.