Hi Julie,

I suspect that you have Japanese beetle grubs eating your grass roots. Dig up the ground about 3-5 inches in a few places and look for fat, white grubs that are curled up.

https://extension.umn.edu/yard-and-garden-insects/japanese-beetles

This link tells you how to manage them but, it's very hard to really get rid of them. There is no easy or even thorough way to keep them from coming back because they lay their eggs in your neighbors yards and then just fly over to your house.

I can tell you that they prefer moist soil ( so don't water your lawn)  and they probably will eventually decline as our native birds learn to like to eat them. Turkeys like the grubs, so if you have any wild turkeys around they might come and dig the grubs up for you.

Good luck,

Sally Granath

St. Louis County MG