What Are Lawn Grubs
Grubs are the larval stage of several beetle species: Japanese beetles, European chafers, and June bugs. Adults lay eggs in lawn soil in June and July. Eggs hatch into C-shaped white larvae that feed on grass roots from August through October, then burrow deeper to overwinter. They return to the root zone in spring, feed briefly, then pupate into adult beetles that repeat the cycle.
How to Identify Grub Damage
Grub damage appears as irregular brown patches that don’t respond to watering. The key diagnostic: grab a handful of the dead grass and pull. If it comes up like loose carpet with no root attachment, grubs have eaten the roots. Peel back a 1 sq ft section of turf in the transition zone between healthy and damaged grass. Count the grubs: more than 5 per sq ft warrants treatment. Healthy lawns can tolerate up to 5 per sq ft without visible damage.
Secondary Damage
Grubs attract predators that cause additional lawn damage. Skunks and raccoons dig up turf at night to eat grubs, leaving torn patches. Birds (crows, starlings) peck holes in the lawn. Moles tunnel through the root zone following grub populations. Treating the grubs eliminates the predator attraction.
