Southern Corn Billbug
Egg - The kidney-shaped, cream-colored egg is about 3 mm long and 1 mm in diameter.
Larva - The grub is cream colored and legless with a distinct reddish-brown head. It ranges from 2 to 12 mm in length, depending on its maturity. Color plate.
Pupa - The pupa changes from a cream to a reddish-brown color in 7 to 10 days and is about the same size as the adult.
Host Plants - The southern corn billbug appears to prefer corn, but also attacks sorghum and several species of sedges, particularly nutsedge.
Damage - Adults feed on the tender inner tissue of seedling corn. During feeding their beaks pierce through the outer leaf sheath into developing tissues causing dieback of terminal blades, rows of transverse holes on the blades and excessive suckering in plants which survive. In addition to adult attack, larvae develop in and around the underground portion of the stalk. Extensive damage is generally restricted to nonrotated cornfields or to areas adjacent to the previous year's corn. Color plate.
Life History - The overwintering adults, which rarely fly, emerge during April and May from litter in fields, ditches and hedgerows. Each female feeds, mates and lays about 200 eggs, usually at night. They are laid in holes chewed out by the female in the basal area of the host plant. In 4 to 15 days, tiny legless, grublike larvae hatch, migrate down the outside of root crowns, and feed in roots and lower stalks. There is usually only one larva per cornstalk though as many as five have been known to attack the same stalk. The larvae develop in 40 to 70 days and pupate in or around the excavated taproot. Most pupae occur from July to September. Adults develop in 7 to 10 days and either remain within pupal cells or emerge to feed before hibernation. There is only one generation per year.
