Saturday, before mowing my front yard, I discovered them in my Bermuda lawn. So be on the lookout for them if you have Bermuda.
With a minor infestation, your grass will look browner than normal. Major infestations can destroy your whole lawn overnight. The armyworms eat the grass blades and leave the brown stems.
If you suspect your turf is being infiltrated but can’t find the caterpillars in the grass, just squat down and watch the grass blades closely. If the worms are there, you will see the grass blades moving.
You can also use a soap flush to bring them to the surface. Fill a 2-gallon bucket with water and squirt some dishwashing liquid it in (about 1/2-ounce dishwashing soap per gallon of water).
Young armyworms are ¼ to ¾ of an inch long. Mature ones are 11/2 inches. They are dark with several light stripes down the length of the body. The head or face has an inverted “Y” on it.
If you have to treat your lawn, carbaryl (Sevin), trichlorfon (Dylox), imidacloprid (Merit), cyfluthrin (Bayer Advanced products), bifenthrin (Ortho Max) and other pyrethroids are the best insecticides to treat with. Organic products include Spinosad and Bt. products (Thuricide and Dipel).
Irrigate before treating to move the caterpillars out of the thatch layer of the grass. Treat lawns during early evening or as late in the day as possible when the worms are likely to be feeding.
If possible, mow the grass before you treat then don’t mow for three days after the treatment.