Dealing with grubs in a lawn is not terribly difficult once you have clear in your mind their life cycle. The grub is up near the surface, under your grass, in late spring and then again in late summer/early fall. During that time you use a product that can get to the grub when it is underground.
When the grub hatches into a beetle, that beetle is vulnerable to control using tools that kill pest insects above ground. See the file Controlling Japanese Beetles for more information about dealing with the grub in its adult stage.
The solutions discussed here all attack the grub when it is in its shallow underground stage.
There is a short term solution and a long term solution to a grub problem.
Grubs In The Short Term – If you have enough grubs to be causing visible damage you need to address that problem immediately. There are no organic insecticides that will kill grubs in the short term. So we recommend a one time use of a grub insecticide containing the active ingredient "Merit"; e.g. GrubX by Scotts or Season Long Grub Control by Bayer.
We recommend these synthectic products hoping that you will use them only once and then proceed to the long term steps that allows you to control grubs at the same time reducing the use of synthetic pesticides in your yard.
Grubs In The Long Term – Grass with a deep root system living in a healthy soil with sufficient organic matter will have no problems from grubs. Japanese beetles don’t like to lay eggs in grass two inches or taller; mow tall. If the three groups of beneficial insects (ants, spiders, and ground beetles) are present they will consume 80% of any eggs laid by Japanese beetles within 48 hours of those eggs being laid. Grass with a deep roots system has such a mass of roots that you can have 15 white grubs per square foot and never know they are there. Go to https://gardening.yardener.com/CaringForSoilUnderTurfgrass.html to learn how to reach this long term solution