The best time to apply preventative grub control in southeast Ohio is during the early spring just before the grubs hatch. Putting down insecticide in late spring is futile; full grown grubs do not eat as much. If the early spring application is missed, wait until late summer to apply.
Adult beetles flying around is a signal to put down the preventative grub control product. To check for grub problems, pull back a square foot of turf or soil from an area in the yard. Six or more grubs means signals a grub issue. Irrigation after the application of grub control is essential, the insecticide then sinks deeper into the soil reaching the grubs.