This is one of the worst years on record for fall armyworms as a pest in home lawns, and specifically cool-season grasses. Normally, fall armyworms are a pest in agriculture crops, or feed on warm-season grasses, such as bermudagrass on golf courses. We are not used to seeing them in cool-season lawns like they are this year. Lawns started turning brown practically overnight and can look very brown and dead.
A fall armyworm is a grayish-to-greenish worm with stripes running down the body, an inverted “Y” on its head and is about 1.5 inches long. They get the name “army” because they feed in groups and progress from one area to another as if they were marching. Fall armyworms do not feed on grass roots, but on the blades, which causes damage and makes lawns turn brown very quickly. They mostly feed during the very early morning or late in the evening. You might not see them during the day as they tend to hide in the thatch of lawns to avoid ultraviolet light.
Lawns will recover from armyworm damage, but you may have to reseed. If we have cooler weather and plenty of rain this fall, our cool-season grasses may recover some. Fall armyworms do not overwinter in Kentucky and will disappear after the first frost.
Contact Laurel County office of the University of Kentucky Cooperative Extension Service for recommendations on ways to limit armyworm damage.
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Source: Ray Tackett, UK extension horticulture agent