Fall Armyworm

Spodoptera frugiperlathis caterpillar of the family Noctuidaefeeds on the leaf tissue of a wide variety of crops, including almost all our grass varieties such as bermudagrass, paspalum, fescue, rye grass, etc.

Its adult stage is a greyish butterfly that feeds on nectar at dusk, when it is most active. Eggs are laid at night on lighted areas, and hatch 2 to 4 days later, giving rise to caterpillars that reach a size of up to 40 millimetres in the final stage, about two to three weeks after hatching, and it is at this stage that they are most damaging. At this time they bury themselves in the soil and form their chrysalis, from which they will emerge after about 12-14 days.

They are present in late summer or autumn, with up to 3 or 4 generations occurring each year. Damage seems to occur overnight, as the adult caterpillars move quickly in search of food. The first damage is caused by dehydration as the leaf tissue is destroyed.

Treatment with contact insecticides is necessary when the number of caterpillars is 3 or more per square metre. The best time for treatment is early or late in the day, as they are more active. Insecticides such as Carbaryl, Methyl Parathion, Zeta Cypermethrin, etc. are particularly effective and volumes of water greater than 300 litres per hectare should be used. Control of larvae larger than 20 millimetres can be difficult.