Armyworm Invasion?

Wise County agriculture producers should be checking their Coastal bermudagrass pastures for armyworm invasions.  August rains in the area has really sparked a growth and greened up of the bermudagrass, making it very attractive for the egg-laying moths and hungry armyworm larvae.  In addition to feeding on Coastal pastures, they can also be a major problem in home lawns so be on the lookout.  If you sense that you have a problem, but aren’t sure, give me a call at the Extension office and I’ll be glad to help.

             The fall armyworm is the most common species at present, whereas the true armyworm occurs in the spring. The fall armyworm moth has a wing span of about 1 ½ inches and is dark grey with white markings on the wings.  Eggs are laid in masses of 50 to several hundred on grass leaves. Egg masses are covered with grey scales from the female’s body.  Eggs hatch in about 3-5 days. Larvae vary in color from pale green to almost black.  The life cycle from egg to adult requires about 4 weeks, depending upon temperature. Fall armyworms could be active until frost.

            The fall armyworm is attacked by several species of parasitic wasps and flies which help keep armyworm numbers low.  These benefits are apparently less effective during cool, rainy weather, allowing armyworms to increase. Also, armyworm moths can fly long distance and quickly increase before natural enemies can “catch up”. The result is an armyworm outbreak. Generally, 3-4 armyworms per square foot warrant treatment depending upon crop condition.  As we plant small grains for early grazing, newly emerged wheat cannot tolerate that many. Young worms are more susceptible to insecticides. It is estimated that 80 percent of the crop damage occurs in the last 3-4 days of the armyworm’s life. For this reason, damage seems to occur almost overnight. Sevin 80S, Sevin XLR and Mustang Max are just a few insecticides labeled for controlling fall armyworms.  However, if you’d like a list of other approved products give me a call. Some products do have a waiting period from application to harvest so be sure to read and follow the directions on the label.