Lawn Grub Treatments in Idaho

Japanese beetles, among other pests, develop from grub larvae.

Lawn grubs are a common insect pest in Idaho lawns. They can be hard to control as they mature. Scarab beetles and May and June bugs lay eggs in the summer which become grubs. They do their damage by feeding on the root systems of turf.

Symptoms

If sections of your lawn can be rolled up like a rug, you have grub damage.

Grub damage in the lawn is easily distinguished from other lawn insect problems. Grub-damaged lawns have sections of damaged turf that while still green, can be rolled up like a carpet. Shortly after this stage, the affected patches turn brown and die as they are unable to sustain themselves without roots.

Grub Identification

Grubs are true insects as identified by their six legs.

Lawn grubs are easily identified by their characteristic "c" shape. They have white bodies, yellow or brown heads and three pairs of legs. They range in length between 1/2 to 1-1/4 inches long.

Treatment

Get even coverage at the soil level for best grub control.

Treatment for lawn grubs is most effective after the adults have laid their eggs in the soil in late summer to early fall. Use a granular lawn insecticide labeled for grub control and water it in after application so that it can penetrate thatch layers and contact the young grubs.

References

• University of Idaho: White Grub (Polyphylla decemlineata)
• University of Idaho: Beetles and Grubs
• University of Idaho Extension: Lawn and Turf -- Insects