The best time for grub control is during the fall, before winter frost sets in, according to Bayer Advanced. During this time, the grubs are still close enough to the surface to be dealt with.
While some grub control is possible during the spring, the grubs tend to eat less during that period, making it less likely that they ingest any pesticides. In addition to pesticides for grub control, spiking the grass with spike sandals to aerate it can be a successful way to diminish the grub population. Before the grass is spiked, the lawn should be watered with between 1/4 and 1/2 inch of water to bring the grubs nearer to the surface. Dry soil should be watered the day before applying pesticides.