Mature larvae burrow into the soil or under debris to pupate. Three to four generations occur each year, but only the first one attacks small grains. During years of high population pressure, barley may experience more damage. Sawfly larvae prefer to feed on the stems and are potentially more damaging than armyworms. Larvae begin to climb and feed on stems when the larvae are half grown and the grain is in the tiller to head stage.
Larger larvae feed heavily on the leaf blades and weeds.
This stage lasts six to eight days before moving into the soil to pupate. Heavy defoliation of the flag level can result in significant economic loss. Unlike the sawfly, armyworms begin head clipping only when all vegetation is consumed and the last succulent part of the plant is the stem just below the grain head. Larvae can feed on the kernel tips of wheat, resulting in premature ripening and lower test weight. On barley, significant stem clipping can occur in a short time.