This is a less effective time for control since the grubs are large and are not feeding as actively. The best time to control grubs is when they are small and close to the surface. This ranges from late July until early September. Whichever method is used make sure the soil is moist prior to application and is well watered afterwards. The water is required to move the control products down to where the grubs are feeding underneath the grass roots.
Parasitic nematodes are microscopic worms which infect and kill grubs.
They are purchased as a sponge which contains millions of nematodes. The contents of the sponge are mixed with water and applied to the turfgrass surface in a similar fashion as an insecticide spray. Soil moisture is very important when using nematodes since they will die in drought conditions. The nematodes will not overwinter in the soil so will need to be re-applied every year. The beetle which is the most damaging in its adult stage is the Japanese Beetle.