Therefore, they usually reach damaging numbers only during periods of prolonged wet weather or where abundant crop residue keeps the soil surface moist. Damage occurs most commonly following a forage or plowdown crop, especially in fields that were spring-plowed. Because of the crop residues on the soil surface, slugs may also be more prevalent in fields where minimum tillage systems are used. At present, there is no recommended means of chemical control for slugs in field corn. When fully grown, they will reach a length of 4 to 5 cm.
Armyworms feed on the leaves of grassy plants including corn.
The first sign of damage will be a few gouges in the edges of the leaves. In severe infestations, the leaves may be completely eaten except for the midribs. The adult of the armyworm is a light-brown moth that is active only at night. Eggs are laid during June in thick grassy growth. Therefore, armyworms are more commonly a problem in fields if grassy weeds are not controlled properly.