Field Identification
White grubs are the soil-dwelling larvae of scarab beetles, creamy white with brown heads and three pairs of thoracic legs in a C-shape. They consume roots of turf, ornamentals, and row crops, producing irregular dead patches and easily lifted sod. Adults may be Japanese beetles, June beetles, masked chafers, or other regional scarabs. Populations cycle with weather and adult feeding and oviposition habits.
Cut a square foot of sod at the margin of injury and count larvae -- compare thresholds for your grass type and use case. Examine the raster pattern on the terminal segment for genus clues. Birds and skunk diggings are secondary signs of high density. Separate from wireworms and from crane fly leatherjackets using leg presence and body shape.
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How to Deal With It
Organic Control Methods
Heterorhabditis bacteriophora nematodes infect many white grub species when soil is warm and irrigation follows application. Metarhizium anisopliae is labeled in some regions. Milky spore is specific to Popillia japonica in parts of its introduced range -- do not expect it to control unrelated scarabs. Ground beetles and ants eat eggs.
Reduce night lighting during adult flights of light-attracted species. Maintain moderate fertility and overseed thin turf. Use endophytic grasses where they help your complex. Rotate vegetable beds away from chronic hot spots.
Raise mowing height and aerate compacted soils. Delay planting sensitive crops until after tillage exposes grubs to birds when rotation allows. Inspect nursery liners for root feeding before orchard establishment.
Solarize future beds. Hand pick when preparing planting holes on small sites. Roll back sod locally, remove grubs, and reseat.
Nematodes are the primary organic rescue with strong evidence when applied correctly. Neem drenches vary by species. Avoid prophylactic broad-spectrum soil insecticides in organic systems -- scout first. Repeat nematode applications across instar windows when labels allow.
Let Nature Handle It
Natural Enemies
- Nematodes
- Ground Beetles
- Birds
Threat Map