White Grubs (Phyllophaga spp.)

Life stages: eggs, larvae, pupae, adult beetles.
The larvae of June beetles are the most important white grubs attacking potatoes. White grubs prefer sandy soils and are rarely pests in heavy, poorly drained soils. They are most likely to damage potatoes growing in land previously in sod.
The life cycle of this insect lasts 3 years.
❚ First year: In the spring, the females lay eggs in grassland or in patches of grassy weeds in cultivated fields.
Small, white grubs hatch in 2–3 weeks and feed mainly on fine roots. The larvae then move down into the subsoil for the winter.
❚ Second year: As the soil warms the following spring, the small grubs move upward to feed on roots and tubers, causing severe damage. The grubs, nearly full grown, remain in the soil for the second winter.
❚ Third year: Early in the summer of the third year, the grubs pupate. Later in the season, the adults emerge, but remain inactive buried in the soil. The adults overwinter in the ground, then emerge the following May and June.