Variations in color coupled with sexual dimorphism mean a handful of Fall Armyworm Moths can line up, and none of them are identical.
The male and female moth for this species look different from each other. The female is more gray than brown. The male is more brown than gray. Both have bean-shaped reniform spots on the lower part of the forewing. A short, pale line may be present above this spot, but it does not pass beyond the major vein on the outer edge. An elliptical or tight oval ring or spot is on the upper part of the forewing. It may be filled in with white, orange, or brown coloring. Besides the distinct spots and lines, females tend to be uniform in color, but males can have mottled white, brown, gray, and orange patches all over. This makes it difficult to recognize it unless one is familiar with this species' variations.
The Fall Armyworm, its caterpillar, is a notorious pest. It eats a variety of grasses and crop plants, which means it ruins turf and food production. Peanut, rice, soybean, sugarcane, alfalfa, cotton, and corn are some of the victims of the Fall Armyworm's feasting. Many generations can be produced in one year, so an area can be defoliated over the course of a season. There are many instars to this caterpillar and its appearance changes. One instar has an orange head, a black upper body with yellow lines and specks, and a yellow belly. Another is green with a black head. It can also appear brown with a lighter, yellow stripe on the 'back' that is dotted with dark spots, each growing a short black hair.
This caterpillar is active from late summer through the fall season in the north, but it is active year-round in the southern part of its range. Moths migrate north when the weather warms and help establish populations there. Look for clusters of white or pale yellow eggs covered with fuzz on the underside of leaves. Planting early in the season allows a crop to get harvested before the caterpillars are in force. Chemical and biological controls are commonly implemented to manage infestations when they occur.
Scientific Name: Spodoptera frugiperda
Butterfly or Moth
Size (Adult; Length): 16mm to 19mm (0.62in to 0.74in)
Note: An insect's reach is not limited by lines drawn on a map and therefore species may appear in areas, regions and/or states beyond those listed above as they are driven by environmental factors (such as climate change), available food supplies and mating patterns. Grayed-out selections indicate that the subject in question has not been reported in that particular territory. U.S. states and Canadian provinces / territories are clickable to their respective bug listings.
Butterfly and Moth Anatomy
Antennae: Butterflies and Moths have a pair of antennae on the head used as sensors.
Head: The head is home to the insect's eyes, antennae, and proboscis.
Thorax: Home to the three pairs of legs as well as vital internal organs.
Abdomen: Contains vital internal organs such as the heart(s) and reproduction facilities.
Forewing: The upper, forward wing pair used for flying.
Hindwing: The lower, rearward wing pair used for flying.
NOTE: Butterflies and Moths are part of the Lepidopteran order as they share many similarities.