Grubworms in Zoysia Grass

Identification

• The Texas A&M University Extension cites white grubs as a major pest of zoysiagrass. The pests are the larval stage of scarab beetles. The distinctly C-shaped grubs are ¼ to 2 inches long and creamy white in color with brown heads and three pairs of legs.

Damage

• The pests feed on grass roots. Initial symptoms include thinning and yellowing turf. Damaged grass gradually starts to die, creating dead patches of brown grass on turf. Infested areas get spongy and soft and grass pulls up easily. White grub infested lawns are also prone to damage from secondary pests including raccoons, moles and birds.

Control

• The use of natural white grub predators like parasitic nematodes from the Steinernema or Heterorhabditis species provide effective control. Introduce the nematodes in soil as soon as you find grubs. Apply insecticides with long-term residual effects. These include thiamethoxam, imidacloprid or halofenozide.