Zoysia is a warm-season lawn grass popular for its drought tolerance, deep green color, coarse texture and the way it stands up to foot traffic. Like most lawn grasses, Zoysia is subject to a few common pests, and white lawn grubs are most common among them. Grubs feast on the roots of the grass until they mature into adult beetles. If an infestation has developed where you can view more than four grubs in a square foot of soil under the grass, intervention is called for to keep the population in check.
Spray the Zoysia lawn in the mid-summer with an insecticide product containing active ingredients such as Imidacloprid or Halofenozide that are known to be effective on white grubs. Follow the label instructions for dosage.
Water the lawn until it's thoroughly wet before applying the insecticide. Spray the insecticide carefully onto the lawn surface. Water the insecticide into the lawn to drive it down to the grubs unless otherwise advised by the product label.
Introduce nematodes or beneficial worms to infiltrate the grubs for an organic solution. Sprinkle the nematodes onto a pre-watered Zoysia lawn in the late afternoon and water into the soil right after application.