If your lawn is turning from green to brown faster than normal, it’s best to look for a pesky insect.
Armyworms are known to feed on lawns, plants, and other vegetables. Although armyworms turn into moths later in life, the larvae do most of the damage. So, how big of a threat are they in Kansas?
According to Raymond Cloyd, professor of entomology at Kansas State University, there was a serious infestation of fall armyworms in Kansas in 2022.
“They caused significant damage, entire lawns and turf were damaged,” Cloyd said.
Cloyd said armyworms haven’t been a major problem since then, but he has noticed an increase in calls in 2024.
“I have images of grass that has been completely eaten and destroyed,” Cloyd said.
Armyworms come to the Midwest as moths and lay masses of eggs on plants and other structures. When those eggs hatch, the damage begins. Fall armyworms in Kansas usually lay eggs in July and continue to breed through August and September.
“You find egg masses on structures like lawn chairs on patios,” Cloyd said. “The caterpillars emerge, they crawl down and start feeding on the grass.”
There are two types of army caterpillars to look out for: the autumn army caterpillar and the true army caterpillar.
Fall armyworms, which would cause damage now, are usually half an inch long. You can tell it’s a fall armyworm by the inverted Y shape on its head.
Male moths can be identified by the grey-brown colour of their wings with white spots at the tip and middle of the wings. Females can be identified by their grey-brown wings with fewer markings than male armyworms.
According to K-State, the true armyworm usually emerges in late spring. You can recognize a true armyworm larva by its greenish-brown body with a stripe and a 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 that preventing armyworms is nearly impossible. So if you’re worried about an infestation, the way to prevent long-term damage is to pay attention now and know the warning signs.
Early warning signs of an infestation may include small gnawing patterns on leaves.
If you see unusual brown patches in your lawn, Cloyd recommends checking the base of your grass for armyworms. You should also keep an eye out for egg masses.
Egg masses are usually brown or tan and covered with down. They can contain about 50 eggs each. Cloyd said he’s seen about 20 to 25 egg masses on one porch this year.
Cloyd said you can remove egg clusters with a pressure washer. But if you see significant damage caused by armyworms, it’s best to call a trained professional.
