Grubs of various insects are one of the most common pests to afflict the ordinarily hardy zoysiagrass lawn species. These grubs may not only detract from your yard's appearance, but may feed on your grass's shoots and roots, causing widespread damage to your lawn. Defend the health and beauty of your landscape by killing the grubs in your zoysia by preparing your lawn then applying an insecticide that won't harm your grass.
Measure your lawn's thatch by separating the grass with your hands and using a ruler to measure the brown layer under the green grass. If it is 1/2 inch deep or deeper, you will need to dethatch your lawn to allow insecticide to penetrate.
Dethatch your entire lawn using a vertical mower or mechanical dethatcher, both available as rentals from most nurseries and garden stores.
Apply a standard lawn insecticide formulated with carbaryl, or a imidacloprid- or halofenozide-based lawn product specifically formulated to target grubs. Administer according to the product's guidelines, because toxicity varies by brand.
Water your lawn lightly with enough water to moisten the soil to a depth of 1 inch. This helps transport the insecticide's chemicals to the zoysia root level to kill all grubs.