INSECT APPEARANCE: The armyworm caterpillars are light tan to dark brown with yellow, orange, or dark brown stripes down the lengths of their backs. They are 3/4 inch to 2 inches long. Adult moths are tan or mottled gray with a wingspan of about 1 inch. They fly only at night or on overcast days. In daylight, they hide in the soil around grass roots.
LIFE CYCLE: Moths appear in late spring to early summer and lay hundreds of eggs at a time on the grass. Larvae hatch from eggs within 10 days and begin feeding. You may see the larvae hanging from threads on the grass. In the South, there may be as many as six generations a year.
DAMAGE THRESHOLD: More than five larvae per square yard indicates infestation.
CONTROL: Spray with Bacillus thuringiensis, carbaryl, chlorpyrifos, diazinon, neem, or pyrethrum. Or, treat with diazinon or chlorpyrifos lawn granules, which also work effectively.