Description

Fall armyworm adults are large bodied moths with dark grey forewings that have lighter banding. A light spot occurs near the apex of the forewings. Mature larvae are up to 1.5 in. long and are dark brown in color with numerous black spots (Photo 5-26). The head capsule has a distinct light colored inverted “Y”.

Distribution, damage and impact

Fall armyworm occurs throughout Arkansas and its impact on field corn is similar to that of the corn earworm.. This impact occurs in several forms including foliar damage to young corn, damage to tassels and silks, and direct damage to kernels. The fall armyworm also plays a role in occurrence of aflatoxin. Damage to corn ears may serve as an entrance for the fungi responsible for producing aflatoxin.

Life History

In early spring adults migrate into Arkansas from more southern states, mate and seek suitable host plants for egg laying. Eggs are laid in masses that contain up to a few hundred eggs. Emerging larvae feed for two to three weeks and then pupate just below the soil surface. Multiple generations occur each year.

Management

Foliar insecticides are not practical for fall armyworm management on field corn and their use may ultimately increase the problem. Numerous beneficial organisms affect larvae including naturally occurring insect pathogens, parasites and predators and insecticide use may reduce their effectiveness. The use of transgenic Bt corn likely has some impact of reducing damage to foliage and ears. Future transgenic lines may possess much stronger toxicity to the fall armyworm.

Insecticide recommendations for fall armyworm on field corn

See Table 5-2 for insecticide recommendations current at time of publishing. Current updated recommendations can be found in the Cooperative Extension Service publication MP-144 and on the world wide web at WWW.cdms.net/manuf/default.asp. Always follow instructions on pesticide labels.