Fall is the best time to inspect for grubs, although early spring can also bring on early infestations. At these times the grubs are near the soil surface feeding at the root zone. Use a spade to cut three sides of a strip one foot square and three inches deep.. After inspection, replace the strip of sod to insure roots can re-establish contact with the soil. Repeat this procedure in several other areas of the lawn to locate possible white grub infestations.
For white grub elimination, treat with Merit insecticides. Two types of Merit systemic products are available: Merit Granules and Merit Spray Concentrate. Both work but most professionals prefer using the granular Merit Systemic Insecticide. Water the insecticide well, in order to deliver the material deep enough to kill the grubs.