Fall Armyworm

Fall Armyworm - larva and adult
Fall Armyworm (on corn)

The Fall Armyworm (Spodoptera frugiperda) is a specific type of armyworm in the moths and butterflies order (Lepidoptera).  The adult stage is a moth.  The hairless caterpillars vary in their coloring, from tan, to green, to nearly black, and they can wreak havoc with many grain crops (especially corn) and grasses such as timothy when their populations are high. The ‘armyworm’ name is derived from its feeding habits. They will eat everything in an area and once the food supply is exhausted the entire ‘army’ will move elsewhere in search of an additional food source.

Photo showing a corn plant with leaves damaged by Fall Armyworm larval feeding
Corn damage caused by Fall Armyworm larval feeding

An infestation is hard to detect as the caterpillars can migrate to new feeding areas in the cool and darkness of the night. When the caterpillars near maturity, they can lay waste to an entire crop in a few days.  Early Fall Armyworm damage in corn appears as small, circular holes (often referred to as shot-holes) in the leaves. Damage from larger, more mature caterpillars results in ragged leaves, and as the corn ears develop further, the caterpillars migrate from the whorls to the ears and damage the kernels.

Additional Information: Managing Insect Pests of Sweet Corn