Grubworms are the larval form of various beetles, the Masked Chaffer being the most damaging in Kansas. When the grubs are at their largest in late summer they can do considerable damage to lawns by eating the roots of the grass. They are white with red heads and often curl into a “c” when dug up. Grass that has been damaged by grubs can be differentiated from other lawn problems by pulling on the blades of grass. If the grubworms have damaged the roots, the grass will easily lift up, often like a carpet. The damage generally appears in late summer.
If a high-quality lawn is desired, a seasonal control such as Hi-Yield’s Grub Free Zone can be applied in early July over the entire area. For areas where some damage is acceptable, Bayer’s 24 Hour Grub Killer can be applied on areas where the grass is thinning or discoloring in August. Control is generally best if the lawn is watered well before the chemical is applied to bring the grubs to the surface, then afterward to water the product into the soil.