The pupal stage of fall armyworm cannot withstand protracted periods of cold weather. The moths has a wingspan of 32 to 40 mm. In the male moth, the forewing generally is shaded gray and brown, with a triangular white spots at the tip and near the center of the wing. The forewings of females are less distinctly marked, ranging from a uniform grayish brown to a fine mottling of gray and brown. The hind wing is iridescent silver-white with a narrow dark border in both sexes.
Adults are nocturnal, and are most active during warm, humid evenings.
After a preoviposition period of three to four days, the female normally deposits most of her eggs during the first four to five days of life, but some oviposition occurs for up to three weeks. Duration of adult life is estimated to average about 10 days, with a range of about seven to 21 days. Ashley et al. This species seemingly displays a very wide host range, with over 80 plants recorded, but clearly prefers grasses. The most frequently consumed plants are field corn and sweet corn, sorghum, Bermudagrass, and grass weeds such as crabgrass, Digitaria spp.