How to Control Grubs and Lawn Pests

Before spending money on treatment, verify that grubs are actually the issue. Choose a brown or spongy area of your lawn and use a flat-blade spade to cut three sides of a 1-foot square, about 3 inches deep. Peel back the sod flap like a carpet and count the white, C-shaped grubs in the exposed soil. Six or fewer grubs per square foot is normal and doesn't require treatment — a healthy lawn can tolerate that level. Ten or more per square foot means you have an infestation that needs action. Check 3-4 spots across the lawn to get an accurate picture, then press the sod flap back down and water it.

Timing determines which product you need. If it's late spring or early summer (April through mid-July depending on your region) and you want to prevent grubs before they hatch, use a preventive product containing chlorantraniliprole (Scotts GrubEx) — this is the most effective approach, killing 75-100% of grubs. If it's late summer or fall and you're seeing active damage from grubs already in the soil, use a curative product containing trichlorfon (BioAdvanced 24 Hour Grub Killer Plus) or carbaryl — these work on contact against existing grubs. For an organic approach, apply beneficial nematodes (Heterorhabditis bacteriophora) in late August or September when grubs are small and near the surface.

Check the product label for the recommended spreader setting and application rate — GrubEx, for example, calls for 2.87 pounds per 1,000 square feet. Set your broadcast spreader to the dial number listed on the bag for your spreader brand (Scotts, Earthway, etc.). Pour the granules into the spreader hopper on a hard surface like a driveway — never on the lawn, where a spill could burn the grass. Close the hopper gate before moving to the lawn.

Walk at a steady pace across the lawn, making parallel passes with the broadcast spreader. Overlap each pass by about 6 inches to avoid leaving untreated gaps — missed strips are where grubs will survive and continue feeding. Walk the perimeter of the lawn first, then fill in the interior with back-and-forth passes. Cover the entire lawn uniformly, not just the damaged areas — grubs can be present throughout the soil even where the grass still looks green. An average 5,000-square-foot lawn takes about 15 minutes to cover.

Within 24 hours of application — ideally immediately after — water the entire treated lawn with at least half an inch of water. This is the single most critical step: the water dissolves the granules and drives the active ingredient down through the thatch layer into the soil where grubs live. Without watering, the product sits on the grass blades, breaks down in sunlight, and never reaches the grubs. Use a sprinkler and set out a tuna can or rain gauge to measure when you've hit half an inch — most sprinklers take 20-30 minutes to deliver that amount.

If you prefer an organic approach, apply beneficial nematodes (Heterorhabditis bacteriophora) in late August or early September when soil temperature is 60-85°F and young grubs are feeding near the surface. Nematodes are living organisms that come refrigerated — mix the contents of the pack with water in a watering can or hose-end sprayer according to the package directions (typically one pack per 2,000-3,000 square feet). Apply in the early morning or evening when the sun is low, since UV light kills nematodes. Water the lawn thoroughly before and after application to ensure the nematodes can move through moist soil to reach the grubs.

After treatment, the dead grubs stop feeding within days, but the brown patches won't repair themselves — you need to reseed or resod. For small areas, rake out the dead grass and thatch, scratch the soil surface with a garden rake, spread grass seed at the rate listed on the bag (typically 4-6 pounds per 1,000 square feet for overseeding), and cover lightly with a thin layer of compost or peat moss. Water the seeded areas twice daily until germination (7-14 days for most grass types). For large dead areas over 4 square feet, consider laying sod patches for instant results.