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Billbug Grubs
Billbug Grubs
Billbug Grubs are tiny legless larvae of adult weevils or snout beetles. They are probably the most misdiagnosed lawn insect problem of cool-season turfgrass as the damage they cause mimics drought damage. The larvae are most active from late spring through summer.
Adult Billbug females lay eggs in tiny slits they make in the stem tissue of grass plants. The larvae hatch and begin feeding down through the stem. Eventually, larvae reach the crown and roots, feeding on that area of the plant, which results in plant death.
Damaged turfgrass will look dried out and have small dead patches of grass. Individual dead grass plants can be easily pulled up and deposits of frass, or insect excrement, which resemble sawdust, will be seen at the base of the plant. Unfortunately, by the time the damage is seen, it is too late to apply an insect control as they have finished feeding. Watering and a fertilizer application will help the lawn recover, but serious infestations may require reseeding.
If you discover that your lawn has been damaged by Billbugs, plan on applying a preventative insect control in the spring of the year, before the eggs hatch.