This insect could kill your Kansas lawn. Here’s what to do about armyworm infestations
If your lawn turns from green to brown faster than it usually does, you may want to check for one annoying insect.
Armyworms are known to feed on lawns as well as plants and other vegetables. While armyworms do become moths later in life, the larvaes cause the most damage. So, how much of a threat are they in Kansas?
According to Raymond Cloyd, entomology professor at Kansas State University, there was a bad infestation of fall armyworms in Kansas in 2022.
“They caused substantial damage, entire lawns and turf grass were damaged,” Cloyd said.
Cloyd said armyworms haven’t been a big problem since then, but he has noticed more phone calls in 2024.
“I’ve got images of turf grass entirely fed upon and destroyed,” Cloyd said.
Armyworm will come to the Midwest as moths and lay egg masses on plants and other structures. When those eggs hatch, that’s when the damage begins. Fall armyworms lay eggs in Kansas usually in July, and continues to reproduce through August and September.
“You’ll find egg masses on structures like lawn chairs on decks,” Cloyd said. “The caterpillars emerge, they’ll crawl down and start feeding on the turf grass.”
There are two types of armyworms to look out for — the fall armyworm and the true armyworm.
Fall armyworms, which would be the kind causing damage now, are usually a half-inch long. You can tell it’s a fall armyworm by an inverted Y shape on its head.
Male moths can be identified by the gray-brown color of their wings with white spots near the tip and center of the wings. Females can be identified by their gray-brown wings with fewer markings than male armyworms.
According to K-State, the true armyworm usually comes out in late spring. You can identify a true armyworm larvae by its greenish brown body with a stripe and yellowish head. The true armyworm moth has a wingspan of 1 1/2 inches and is grayish brown in color.
How to get rid of armyworms in Kansas
Cloyd said preventing armyworms is close to impossible. So if you are afraid of an infestation, the way to avoid long-term damage is to keep an eye out now and know the warning signs.
Early warning signs of an infestation could be small nibbling patterns on leaves.
If you notice any unusual brown spots in your lawn, Cloyd recommends checking at the base of your grass to see if you notice any armyworms. You should also keep an eye out for egg masses.
Egg masses are usually brown or tan and covered in fuzz. They can contain about 50 eggs each. Cloyd said he’s seen about 20 to 25 egg masses on a single porch this year.
Cloyd said you can get rid of egg clusters by using a high-pressure power washer. But if you notice significant damage caused by armyworms, the best thing to do is to call a trained professional.
