White Root Grubs
Of all underground insects, white grubs are the most destructive. The grubs often attract moles which become a secondary problem.
Seedlings grow (30-60 cm tall) before they wilt, yellow and die. Damage is patchy in fields. Activity by moles, sod-digging skunks, and raccoons indicates grubs are in the soil.
Grubs hibernate in soil deep beneath the frost line (to 1.5 m. underground). In spring, they return from the deep to feed on shallow roots, spend the summer close to the surface, then return to their deep winter cells. Grubs may run this cycle a third year, depending on the species. Eventually they pupate. Adults emerge from the soil in spring, and feed at night on foliage. At dawn they return to the soil where females lay pearly white eggs in batches of twelve to thirty, under sod or weedy patches of grass. Eggs hatch in three weeks and young grubs feed on roots for the summer.