White grubs are the soft-bodied, C-shaped larvae of various scarab beetles, such as the Japanese Beetle and the June Bug. These pests live just beneath the soil surface, feeding on the fine roots of turfgrass. When the root system is compromised, the grass cannot absorb water and nutrients, leading to irregularly shaped patches of dead, brown turf. A telltale sign of an infestation is the ability to roll back the affected grass like a piece of carpet because the anchoring roots have been severed. Effective grub control requires choosing the correct product and ensuring perfect timing to prevent widespread damage.
Selecting the Right Grub Control Product
Effective grub control requires understanding the difference between preventative and curative treatments. Preventative products stop a grub problem before it starts by targeting newly hatched, very young larvae. These treatments provide season-long protection and are best for lawns with a history of infestation. Common preventative ingredients include imidacloprid, chlorantraniliprole, or clothianidin.
Curative grub killers are fast-acting, contact insecticides intended to eliminate an existing, active infestation. If you discover significant turf damage or a high population of grubs in late summer or fall, a curative product is necessary to rescue the lawn. Active ingredients often include trichlorfon (often branded as Dylox) or carbaryl. Curative treatments are generally less effective than preventative methods and may require a higher concentration of active ingredients to kill larger, established grubs.
Determining the Optimal Time for Treatment
The life cycle of the grub dictates the ideal application window for any control product. Adult beetles typically emerge and lay their eggs in the soil from June to early August. The eggs hatch a few weeks later, and the tiny larvae immediately begin feeding on grass roots in mid-to-late summer.
The optimal window for applying preventative treatments is late spring or early summer, typically May through July, ensuring the active ingredient is present when the eggs hatch. Products containing chlorantraniliprole should be applied earlier, in April or May, because they take longer to move down into the soil. Treatments with imidacloprid should be applied in June or July, closer to the egg hatch, as they are more water-soluble and move through the soil quickly.
Curative treatments are reserved for late summer and early fall, usually August through September, when grubs are actively feeding near the soil surface. Applying a contact killer then targets the grubs before they burrow deep into the soil for winter. Curative treatments applied in the spring are less effective because the grubs are larger and may have stopped feeding, resulting in a success rate as low as 20% to 55%.
Step-by-Step Application Techniques
Proper application of granular grub killer begins with preparing the lawn to maximize the product’s contact with the soil. Mow the turf a day or two before application to ensure the granules reach the soil surface easily. Before opening the bag, accurately measure the square footage of the treatment area by multiplying the length and width. This ensures you apply the correct amount of product; under-application results in poor control, while over-application is wasteful.
Next, the spreader must be calibrated precisely according to the settings listed on the product label for your specific model. Using a push-style drop or broadcast spreader is necessary for even distribution, as handheld spreaders often lead to inconsistent coverage. Load the spreader hopper and walk at a consistent, steady pace to apply the granules across the entire area.
The most effective way to ensure uniform coverage is by using a cross-hatch pattern. Apply half the required amount in one direction and the remaining half perpendicular to the first pass. Immediately after spreading the granules, the product must be activated by watering the lawn thoroughly. Applying at least one-half inch of water moves the chemical down into the root zone where the grubs are feeding. Failure to water in the product significantly reduces its effectiveness.
Essential Safety and Post-Application Measures
Protecting yourself and the environment requires adherence to specific safety protocols. Always wear Personal Protective Equipment (PPE), which should include long pants, long sleeves, closed-toe shoes, gloves, and eye protection, to minimize skin contact with the insecticide. Wash your hands thoroughly immediately after handling the product and before engaging in activities like eating or drinking.
After the application is complete, sweep or blow any granules that landed on hard surfaces like sidewalks or driveways back onto the lawn. This prevents the chemicals from washing into storm drains and local waterways. Keep children and pets off the treated area until the granules have been completely watered in and the grass is dry. This prevents accidental tracking or ingestion of the chemicals while they are still on the turf surface. Store any remaining product in its original container in a secure, locked, cool, and dry location away from children.