Lawn grubs feed on the grass roots, infesting the yard and killing the grass. Fewer than eight grubs found in 1 square foot of lawn usually won't require treatment, but more can severely damage a lawn. Areas of irregular brown patches that can easily be pulled up will need treatment for grubs. The best time to treat the lawn grubs is in June, when they're most vulnerable to insecticides.
Determine Whether You Have a Grub Problem
Select four different spots in the lawn, two in areas where there is visible grass damage and two where there is no visible damage.
Cut three sides of a 1-foot square into each of the lawn areas using a flat-edged shovel to create a flap. Cut down 2 or 3 inches to just below the grass roots.
Lift the sod gently and inspect the soil for the C-shaped grubs. Count the grubs, noting whether there are more than eight to 10 in the spot. Replace and water the sod when the inspection is finished and when you have determined whether those areas need treatment.
Lawn Grub Treatment
Aerate the lawn in the areas where there are heavy grub infestations. Make a single pass across the yard with an aerator to penetrate the soil around the grass roots, where the grubs are living.
Spread a granular insecticide, such as carbayal, onto the affected lawn areas in June, following the dosage instructions on the label. Water the lawn enough to dissolve the insecticide granules.
Repeat the treatment in late summer or early fall if grubs remain in the lawn.
About this Author
Sarah Terry brings 10 years of experience writing novels, business-to-business newsletters, and a plethora of how-to articles. Terry has written articles and publications for a wide range of markets and subject matters, including Medicine & Health, Eli Financial, Dartnell Publications and Eli Journals.