How to Control White Lawn Grubs

White grub damage makes your grass look brown and dehydrated.

The masked chafer is the beetle behind white lawn grubs. It lays its eggs in healthy lawns. When the eggs hatch, the larvae begin to munch on the grass roots. If you notice a brown spot even though your grass has gotten plenty of water, you probably have grubs. Lift up the patch of dead grass. If you see white larvae, discard the sod and hand-pick the grubs. When the infestation is limited to one spot, that's all you may need to do. However, in cases where the grubs are widespread, consider other options to save your lawn.

Things You'll Need

• Nematodes
• Insecticide
• Gloves
• Mask

Instructions

1. Apply Heterorhabditis bacteriophora nematodes to your grass in late summer or early fall. These tiny worms enter the grubs and kill them with bacteria. Water your grass in the early evening. Mix the nematodes with distilled water and put the solution in a sprayer. Apply to the areas that have an infestation. Water your lawn again. Repeat the process in two weeks.

2. Apply synthetic insecticide to kill adult lawn grubs. Use this option as your last resort since it poses risks to the well being of other plants and animals. Rake the lawn to remove dead grass and other debris and water it thoroughly. Broadcast the granules and water the grass again to push the insecticide into the ground. Apply 3 lbs. per 1,000 square feet of grass.

3. Apply insecticide granules to kill the young larvae before they cause damage. Rake the grass to remove debris and water it. Broadcast 30 lbs. of insecticide granules per 1/2 acre of lawn. Following the application, water your lawn again to push the insecticide down to root level.

Tips & Warnings

• Stop watering your lawn in mid-summer. Grubs need moisture to survive. They lay their eggs in well-hydrated grass. If you don't water your grass the second half of the summer, you may be able to prevent white grub larvae. Your grass will look brown because it has gone dormant.

• Wear gloves and a mask when using insecticide.

References

• University of Illinois Extension: Lawn FAQs: White Grubs in Lawns
• University of California, Agriculture and Natural Resources: Beneficial Nematodes

Resources

• Cornell University Extension Toxicology Network: Imidacloprid
• Cornell University Extension Toxicology Network: Trichlorfon
• Green View: Grub Control (Dylox) Product Label