Spodoptera frugiperda or fall armyworm is a common pest of numerous crops in South Carolina. Overwintering sites in North America include south Florida, Texas, Mexico, and the Caribbean. Each year, the insect migrates through much of the U.S., including South Carolina where infestations are generally found starting in June, with populations often increasing later in the season. We were surprised to find last week whorl infestations of fall armyworm so early in the growing season. The female moths lay eggs in masses on corn leaves, and larvae feed on leaves, creating rows of holes. This type of injury occasionally leads to yield losses when population densities are high in a field. Fall armyworm larvae has an inverted Y mark on its head (Figure 1) the distinguish it from related species. More information on the identification and management of fall armyworm can be found in our Land-Grant Press article.
Figure 1: Inverted Y mark on Spodoptera frugiperda larvae. Image credit: Steve L. Brown, University of Georgia, Bugwood.org.
Larvae of fall armyworm were found in our corn field trial located in Blacksville, South Carolina, last Thursday (May 8, 2025). Larvae were feeding on non Bt corn leaves when plants were at the V3 growth stage (Figure 2), with a typical aggregated pattern of several plants in a row infested, followed by uninfested plants. The trial has plots with Bt corn which were not infested with fall armyworm.
Figure 2: Fall-armyworm larvae feeding on corn leaf, Blacksville, SC. Image credit: Author.
