Army worms cause significant damage across lawns, golf courses, and agricultural fields, yet many property owners fail to identify the pest until it is too late. Understanding what army worms look like and recognizing the specific signs of their presence allows for timely intervention and protects valuable turfgrass.
Adult Army Worm Moths: The Flying Stage
The life cycle of the army worm begins with the adult moth, which is often the first stage people notice without realizing its significance. These moths are relatively small, with a wingspan ranging from approximately one to one and a half inches. Their forewings display a mottled brown and gray pattern that provides excellent camouflage against tree bark and dry grass. The hind wings are typically white or light gray with a thin, dark border along the outer edge. While the moths are capable fliers, they are most active at dusk and night, which reduces the likelihood of direct observation.
Distinguishing Adult Moths from Similar Species
To accurately identify the moth as an army worm, it is important to differentiate it from other common flying insects. Unlike the more delicate appearance of certain moth species, army worm moths have a sturdy, robust body structure. Their wings appear slightly hairy compared to the smooth wings of some other moths. Furthermore, the erratic, darting flight pattern they exhibit when disturbed is a key behavioral clue that sets them apart from other nocturnal flyers in the landscape.
The Caterpillar: The Destructive Stage
The stage responsible for the actual damage is the caterpillar, and this is where the question "what do army worms look like" is most critical. Young army worm caterpillars are pale green with a faint, striped pattern running along the length of their bodies. As they mature, they undergo a color shift, developing a brown, tan, or gray appearance. The body is generally smooth and cylindrical, tapering slightly at both the head and the rear end.
A definitive characteristic for identification is the presence of distinct stripes. There are three prominent white, yellow, or orange stripes running down the length of the caterpillar's body. These stripes are usually of equal width and run from the head to the end of the abdomen. Additionally, the head capsule is brown or black, often marked with an inverted white or orange pattern that resembles a tiny, inverted triangle.
Size and Behavior Indicators
When comparing sizes, fully grown army worm caterpillars reach lengths of approximately one and a half to two inches. They move in a characteristic looping motion, arching their bodies forward and then pulling the rear end up to meet the front. This movement is why they are sometimes confused with cutworms, but the side-by-side stripes are a reliable differentiator. When disturbed, they tend to curl into a tight "C" shape and may drop to the ground to seek shelter.
Signs of Infestation and Damage Patterns
Because the caterpillars feed primarily at night, visual confirmation of the insect itself can be difficult. Instead, property owners often first notice the signs of an army worm infestation. The most obvious sign is the appearance of brown, dead patches of grass that appear overnight. These patches start small but expand rapidly as the caterpillars move in groups from one feeding site to another.
To confirm the presence of army worms, gently lift the edges of the damaged grass and look for the caterpillars in the thatch or soil during the early morning or late evening. Another effective method is the "soap flush" technique: mix two tablespoons of dish soap with two gallons of water and pour it over a square foot of affected grass. The soap irritates the worms, causing them to surface within minutes, making identification straightforward.
Key Physical Features Summary
For quick reference, reviewing the specific physical attributes that define the army worm helps solidify identification. Focusing on the caterpillar stage, the creature exhibits a specific pattern of stripes and body shape that distinguishes it from other lawn pests. Familiarity with these details ensures accurate detection before the population explodes.
