ISSUE 15   September 18, 2008


Damage caused by white grubs often becomes evident in late summer and early fall. Look for large patches of dead grass. Lifting the turf beneath dead patches and adjacent green grass often reveals white grubs in the root zone where they have been feeding all summer. Unfortunately, control of white grubs is usually not successful in late summer and early fall. Cool weather causes the grubs to stop feeding and dig deeper into the soil where they become dormant for the winter. It is difficult or impossible to reach the grubs with an insecticide. If active grubs are found in the root zone during late summer, some control can be achieved using carbaryl (Sevin).

White grubs
White grubs (photo by D. Cappaert,
Michigan State University,

The best strategy to control white grubs is to use imidacloprid products labeled for turf grass and apply them in the spring when the grass begins to green up. Imidacloprid is a systemic insecticide that is taken up by the roots of the grass. Grubs ingest imidacloprid when they begin to feed on the roots. Additional applications may be necessary through the spring as older applications wear off and new grubs appear. Be sure to use adequate water to get the insecticide to the roots, but not so much water that the soil becomes waterlogged. Be sure to read and follow the label when using insecticides.

Patrick Beauzay, Research Specialist
Extension Entomology

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