White grubs are the immature larvae of several species of scarab beetles. These extremely destructive turf pests feed on grass roots just below the soil surface, severing roots and causing lawn grasses to brown and die. Japanese beetle larvae and masked chafer beetle larvae present the most serious grub threats to U.S. lawns. In their adult form, Japanese beetles also cause extensive damage to edible and ornamental plants, from vegetables to shrubs and trees.
Identification: White grubs typically grow about 1 inch long. Their soft, plump, gray-white bodies have brown heads and six distinct legs. When disturbed, white grubs curl into a C-shape. Adult Japanese and masked chafer beetles grow up to 1/2 inch long. Japanese beetles are metallic green and copper with white hair tufts ringing their abdomens. Masked chafers are golden to chestnut brown with matching or darker heads, depending on the species. Lighter brown "masks" cover their faces.
Signs/Damage: Grub damage shows itself in spring and fall. Patches of lawn turn yellow or brown and feel spongy beneath your feet. With heavy infestations, you can roll turf back — just like a rug — to reveal severed roots and feeding grubs. To check your lawn, use a spade to lift a 12-inch-square piece of sod about 3 inches thick. Inspect the soil, thatch and roots closely. Healthy lawns tolerate a few grubs, but ten or more per square foot indicates serious grub problems.
Control: Effective white grub control involves reaching these pests at their most vulnerable. Fall treatment targets newly hatched grubs while they're still small and close to the surface. Spring applications treat overwintered grubs as they return to roots and feed. GardenTech® brand offer a highly effective product that kills white grubs and adult scarab beetles by contact and keeps protecting for up to three months:
- Sevin® Insect Killer Granules kill white grubs and adult scarab beetles in lawns, below and above the soil line. For best results, mow your grass at 3 inches or shorter. Then apply the ready-to-use granules with a regular lawn spreader for thorough, uniform coverage. Water immediately after treatment, according to label instructions, to release the active ingredients into the grass and soil.
For additional protection against white grub damage – and damage by adult Japanese beetles – treat beetles in late spring before they can lay their grub-producing eggs. These non-staining products treat scarab beetles in lawns, gardens and foundation plantings, and keep protecting for up to three months:
- Sevin® Insect Killer Ready to Spray attaches to a common garden hose and automatically measures and mixes as you spray. Treat at the earliest signs of beetles or wherever you expect them. Cover all plant surfaces thoroughly.
- Sevin® Insect Killer Concentrate, used with a pump-style sprayer, allows for direct treatment as well as broader coverage. With the easy-to-use measuring cap, it's simple to measure just the amount you need. Add water, mix well, and treat to cover all plant surfaces thoroughly.
Tip: Grubs often attract birds, skunks, raccoons and other insect-eating wildlife to your lawn. Frequent digging and disrupted turf may signal grub infestations.
Always read product labels and follow the instructions carefully, including guidelines for pre-harvest intervals on edible crops.
GardenTech is a registered trademark of Gulfstream Home and Garden, Inc.
Sevin is a registered trademark of Tessenderlo Kerley, Inc.