The adults lay their eggs in sod and white grubs are therefore a problem in corn following sod, particularly run-down pastures. When such fields are plowed, the partly grown larvae can be found, especially if the sod is broken apart and examined carefully. These are small dark beetles about 6 mm long with two yellow spots on each wing cover. These beetles are often numerous in corn fields but do not cause significant damage. This mucus dries out and can be seen in the daytime as a shiny trail over the leaves and soil.
Slugs feed at night, eating especially between the veins of leaves.
This feeding often causes the leaves to split lengthwise, leaving a tattered appearance. If mucus trails or split leaves are seen, slugs can usually be found hiding during the day under stones, clods, and plant debris. The most troublesome slug in corn is the gray garden slug which is 1 to 2 cm long, gray, legless and slimy. Damage to corn is most serious in May and June before the plants are well established. Treatments with a molluscicide are too expensive to be practical in field corn.