Common Name: Armyworm
Latin Name:Spodoptera spp., e.g. exigua, frugiperda, littoralis, Pseudoletia unipuncta
Main Host(s): Field and row crops, e.g. cotton, soybean, cole crops, leafy and fruiting vegetables
Armyworm includes several species including the Beet Armyworm (Spodoptera exigua), Fall Armyworm (S. frugiperda) and Southern Armyworm (S. eridania) in the U.S. Various species are a problem in many parts of the world: in Africa, S. exempta; in Asia, S. litura; in the Mediterranean area, S. littoralis. The designation of “true” Armyworm is reserved for Pseudoletia unipunctata. The adult moths of the Armyworm are strong flyers and migrate to the cooler parts of the regions they inhabit.
Impact & Damage
Females generally lay white to yellow eggs in several rows on the undersides of leaves in lower canopy of the plant. Armyworm larvae hatch from large egg masses and then forage in groups, hence their name. Three generations per year are possible. Following egg hatch, many larvae will be grouped in a mass within a small concentrated area. Larger larvae are enormously destructive. Armyworms begin feeding near where they hatch, and begin to spread out as they grow. Because they feed at night, armyworms can be difficult to control. Pupation occurs in the soil.
Armyworm species feed on a host of field and row crops, from cotton, soybeans to grains such as rice, wheat, sorghum, as well as vegetables including cole crops, leafy and fruiting vegetables. Since most larvae will grow to large size insects they can do considerable damage.
VBC’s XenTari® is highly effective against Armyworm pests. An excellent time to spray XenTari is when larvae are young and concentrated in small areas. At early developmental stages armyworms are most susceptible to Bt. It is strongly recommended that growers apply XenTari within the first week after egg hatch to ensure the pest is controlled while the populations are concentrated and remain in the first or second instar.
Early application of Bt requires knowledge of insect development and scouting. Pheromone traps are available for monitoring adult flight to help discover early when eggs may be laid.
Typically, higher rates of XenTari are used when controlling this pest.