Look here:

Here is a link that might be useful: grubs

Thanks! After looking further, I actually want to apply Imidacloprid not Dylox (in late June). While digging in various locations in the yard this spring I have noticed quite a few grubs. It may not be 10 grubs per square foot, but in some locations it might be close. Since I have not applied any grub control in the past few years, I figure I should do so this year. What rate should I be applying .20% Imidacloprid (I read in that article that some manufacturers do not actually list the correct rate needed to prevent)?

The time to apply grub control is about 4-6 weeks after you see Japanese beetles or June bugs swarming your porch lights. If you don't have the parents, then you can't get the grubs. Don't just apply because you have not had grubs in many years. I've never had them and never used insecticide. Before you apply check to see that you have the critical mass of grubs. Your yard can handle up to about 12 grubs per square foot without you even noticing them. If you find more than that then you can start to get excited about them. They are a summer time issue. If you don't do anything about them all summer, then you don't have to do anything for the rest of the year, because they stop feeding.

Thanks. I am a bit confused though. We don't typically see Japanese beetles and June bugs until late June or early July around here (Chicagoland). 4-6 weeks from then would be in August which seems to contradict the Michigan State University article. Wouldn't that be too late for Imidacloprid?

Grub Control Should be applied in the early summer. My company uses Merit in June or July. This will keep the grubs from making it past the larvae stage and help your lawn tremendously. Occasionally we will use Dylox for special situations but, Merit works really well in most cases.

This post was edited by ProTurfVernon on Fri, Jun 7, 13 at 14:56

Gosh I would hate to be in conflict with Michigan State. I'm the person who goes around hating on compost, aeration, and daily watering.
What article? You never mentioned that you had an article. Why ask here if Michigan State has all the answers?

The general consensus around the Internet lawn forum gurus is that you don't anticipate problems and start spraying. Did you dig around and count the grubs you already have? Do you have more than 12 per square feet. If so then get out your poison. If not then save your money.