White Grubs
Return to insect pests
White grubs (Phyllophaga sp., Cyclocephala sp., Popillia japonica) can be destructive insect pests of sweet corn in Kentucky. Young plants are damaged when the grubs graze on the grass roots just below the soil surface. The root injury reduces the corn’s ability to take up water and nutrients and withstand the stress of hot, dry weather. Several species of white grubs, with life cycles ranging from one to three years, can attack sweet corn. All of these grubs have stout, grayish-to-white bodies with brown heads. Depending upon the species, the mature grub ranges in size from 3/8 to 2 inches long. Most species are curled into a C-shape when at rest.
White grub feeding on corn roots.
(Photo: UK Vegetable IPM Team, University of Kentucky)
Management:
- As with wireworms, white grubs can be more of a problem in certain rotations, particularly following sod.
- When white grubs are abundant, applying a soil insecticide may be the only way to avoid serious damage.
- Seed treatments may not provide sufficient control where grub numbers are high at planting.
