MU Extension reports fall armyworms are occurring in south Missouri. However, we have received calls regarding damage in northwest Missouri.
Damage from this pest can be all of a sudden appear. This pest prefers fescue and orchard-grass.
Several generations can occur in Missouri each year. Identifying characteristics of the insect larvae are four black spots or bumps on the top of each segment with those on the last segment arranged in a square pattern. Larvae typically have six instars and reach up to one-and one-half inches.
Look for larvae early morning or late evening. The economic threshold in grass pastures is to treat if three or more larvae are present per square foot.
When using insecticides for control, use twenty gallons of water per acre. Be sure to follow all label precautions and restrictions.
For more information, contact Wayne Flanary at 660-446-3724 or Andy Luke at 660-425-6434, Regional Agronomists, University of Missouri Extension.