White grubs are the destructive larval stage of several beetles (e.g., masked chafer, Japanese beetle) that threaten Texas lawns. These pests feed on grass roots, causing widespread damage that can quickly destroy turf. Since they spend most of their lives beneath the soil surface, successful management depends entirely on precise timing. Understanding the grub’s life cycle is necessary to apply treatments when the insects are most vulnerable.
Identifying Grub Presence and Damage
The first sign of a grub problem is often irregular, brown patches of grass that fail to green up despite adequate watering. This damage typically appears in late summer or early fall when the grubs are actively feeding on the root system. A more specific tactile cue is turf that feels spongy or unusually soft underfoot, caused by the severed roots beneath the surface.
In severe cases, you may be able to easily roll back sections of the turf like a carpet because the roots holding the sod in place have been consumed. Another common indicator is increased digging activity from animals such as raccoons, skunks, and birds, which forage for the protein-rich grubs. These animals can cause significant secondary damage while hunting the pests.
To confirm an active infestation, sample the soil by cutting back a one-square-foot section of turf and counting the grubs found in the top two to four inches of soil. A count exceeding six to ten grubs per square foot warrants immediate control. This physical inspection removes the guesswork associated with diagnosing turf problems.
Understanding the Grub Life Cycle in Texas
Effective grub treatment relies on targeting the insects when they are small, close to the soil surface, and actively feeding. Adult beetles emerge in late spring and summer to mate, laying eggs in the turf during June and July. These eggs hatch within a few weeks, and the newly emerged larvae begin their destructive feeding period.
The peak time for this feeding activity across most of Texas, including the Central and North regions, is generally from late August through early October. During this window, the grubs are still small and have not developed into their larger, less susceptible stages. Treating outside this late-summer window yields poor results because the grubs are not actively consuming the treated roots.
Applying treatments too late in the fall is ineffective because grubs move deeper into the soil to overwinter once temperatures drop. They become dormant and stop feeding, making it impossible for them to ingest the insecticide. Similarly, spring applications are wasteful, as the grubs are already large and preparing to pupate into adult beetles, a stage resistant to chemical controls.
Choosing the Right Control Strategy
Chemical application depends on whether the treatment is a planned preventative measure or an urgent curative response to active damage. Preventative treatments are systemic insecticides designed to provide season-long protection against grubs before they hatch. These products, often containing ingredients like imidacloprid or chlorantraniliprole, must be applied in advance of the expected egg hatch.
The ideal window for preventative application in Texas is typically from late May through early July, before the adult beetles lay their eggs. When applied during this period, the chemical is absorbed by the grass roots, creating a protective barrier that poisons the young grubs as soon as they hatch and begin feeding. This approach requires forethought and is not suitable for treating an existing, visible infestation.
In contrast, curative treatments are necessary when damage is already present during the active feeding period of late summer and early fall. These fast-acting, contact insecticides, such as those containing trichlorfon or carbaryl, quickly kill the larger, actively feeding grubs. Curative products must be applied directly to the affected areas where grubs are confirmed.
Because curative treatments are less residual, they are best used as a spot treatment in response to confirmed damage, rather than for whole-yard prevention. Regardless of the control strategy chosen, it is paramount to water the lawn immediately after application. This step moves the insecticide down through the turf canopy and into the root zone, ensuring the chemical reaches its target.