How to Prevent Grubs

Chlorantraniliprole (Scotts GrubEx) is the most popular preventive: it can be applied April through June and provides season-long control with low toxicity to pollinators. Imidacloprid-based products (Merit, Bayer Advanced) are effective but must be applied in June and are more toxic to bees. Choose chlorantraniliprole if you can apply in April to May.

Apply in May to early June, before adult beetles lay eggs and before larvae hatch. In the Central Plains, mid-May is ideal. Too early (March) and the product degrades before grubs arrive. Too late (August) and eggs have already hatched, requiring a curative product instead.

GrubEx applies at 2.87 lbs per 1,000 sq ft. Use a broadcast spreader at the setting listed on the bag (Scotts EdgeGuard: setting 4). Walk at a steady pace. Cover the entire lawn, including areas near the property edges where beetles are most likely to land.

The active ingredient needs to reach the root zone where grubs feed. Water in with at least half an inch of irrigation or time your application before a forecasted rain. Without watering, the product sits on the surface and breaks down from UV exposure before reaching its target.

Grub prevention is an annual treatment. Set a reminder for the same window next year. If you skip a year and beetle activity is present in your area, grubs will return. Consistent annual prevention is far cheaper and more effective than curative treatment after damage appears.