Armyworms are invading North Texas: What are they?

They slither across lawns and pastures in a sort of formation, chewing grass, plants and even weeds. Only an inch or inch-and-a-half long, the caterpillars do not look particularly destructive.

Don’t be fooled. Armyworms—named for their tendency to march in troops—have hatched in throngs this fall across North and Central Texas, where they are wreaking havoc.

Gardening groups on Facebook are rife with photos of the caterpillars and once-green lawns turned brown. Lawn care companies say they are receiving far more calls than usual, and agricultural organizations have published alerts.

“Watch for an armyworm feeding frenzy,” warned a headline from agricultural magazine Dairy Herd Management, which said “armyworms can reduce fields to sticks and stubble in a matter of days.”

Sonja Swiger, an entomologist for Texas A&M AgriLife, said a relatively rainy summer and abundance of lush greenery helped produce the bumper crop of armyworms. Swiger said she even spotted the caterpillars feasting near her crepe myrtles at her home in Stephenville, about 80 miles southwest of Fort Worth.

“They feed on grasses, pastures, parks, yards,” Swiger said. “They have a very large palate and can pretty much eat anything.”

Fall armyworms range in color from brown to gray, green or yellow-green, identifiable by an upside-down Y on their heads, according to Texas A&M AgriLife. They have four life stages: egg, larva, pupa and adult.

They feast on grass toward the end of their lives as caterpillars, before forming cocoons in the ground and emerging as adult moths, the last stage of their life cycle. Adult moths can lay up to 1,000 eggs in a single night, often on the undersides of leaves or structures, such as fence posts or house siding.

They typically live just a couple of weeks as adults, but their damage remains. The worms can decimate an entire football field in just two or three days, Swiger said.

Dustin Sykes, who owns Sykes Turf Management in Howe, just north of McKinney, said he began receiving calls about armyworms in August, several weeks earlier than usual. These days, he gets up to 200 calls a week. One woman reported that armyworms ravaged 16 acres of grass in just 48 hours.

“You can actually see the grass moving,” said Sykes, who has worked in lawn care for 15 years. “I’ve seen five acres wiped out overnight, and I’ve seen one house hit and not another house on that block. They’re unpredictable.”

Damage may initially resemble drought stress, according to AgriLife, but can progress to complete loss of foliage if worms are left untreated.

To protect your property, both Sykes and Swiger advised checking for armyworms in the morning and evening when they are most active. According to Texas A&M, infestations of two to three armyworms per square foot may justify using insecticide to protect crops. If left alone, the grass will likely recover on its own.

Fall armyworms are particularly susceptible to cold, so they typically retreat from North Texas in November with the first freeze of the year.

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