After Ray personally inspected the corn field, he indicated that no treatments would be necessary. Ray sent the specimens above. Notice the black stripe above each abdominal proleg of the larva. This feature separates armyworms from other striped larvae that may be found on the field at this time. Although the numbers are not economic, it signals the potential presence of armyworms in some fields.
Armyworms can be very damaging to small grains and corn if present in high numbers.
On small grains, the threshold is 5 worms per square foot. I have no idea who created these thresholds but seem to be the only guidelines at the moment. Infestations usually starts in grasses injured by hail and lodged to the ground. Armyworm moths migrate into the state from the south. Fields with a lot of foxtails also appear to attract armyworm moths.