Identifying and Managing Fall Armyworms in the Southeast

In the Southeast United States, Fall Armyworms are considered a regular and serious pest. Armyworms are caterpillar larvae of various moth species, most commonly the fall armyworm (Spodoptera frugiperda). These pests are named “armyworms” because of their habit of moving in large, destructive groups across lawns and crops, like an army on the march. For the turfgrass industry, they are a particular nuisance to golf course grounds, lawns, and landscapes. While SodStar’s blue-tag certification decreases the likelihood of armyworms from being present in our farm-fresh sod, sod can still become infected post-installation. Here’s a refresher on best practices in armyworm prevention and treatment.

Characteristics of Armyworms:

Appearance: Armyworms are green, brown, or black caterpillars, about 1 to 1.5 inches long, with stripes running down their bodies. They often have a distinctive inverted “Y” shape on their heads.

Life Cycle: Although fall armyworms do not have many specific preferences, newly-installed sod is more attractive and more susceptible to damage. Armyworms hatch from eggs laid by moths on the grass, plants or even trees and mailboxes nearby. The larvae feed on the foliage, creating rapid and extensive damage. Once they mature into moths, they lay more eggs, continuing the cycle.

Damage: Fall armyworm damage in turfgrass is incredibly unique. Armyworms cross the turfgrass surface as a group, creating a visible line between damaged and undamaged turfgrass. Damaged areas will usually originate around a site where egg masses were laid and radiate outward. In lawns, these pests feed on grass blades, leaving behind brown, dead patches, and can completely strip vegetation in a short period. The damage is typically most severe in late summer and early fall.

Why Southeast Turf Managers and Homeowners Should Monitor for Fall Armyworm

Armyworms are especially problematic in warm climates, and infestations can spread quickly. Once they invade, their feeding can destroy large sections of lawns in a matter of days. This is why it’s crucial to act quickly to eliminate them and begin lawn recovery. NC Turf Files has created a new resource for turf managers and homeowners to track the areas impacted by fall armyworms – if you are in an area that is particularly affected by this pest but haven’t experienced infestation yet, it is recommended to take appropriate action. See below.

Use this interactive self-reporting map to report when and where fall armyworm activity and damage occurs across the region. Users can create pins to share and track real-time data. Contribute your own reports, view submissions from others, and stay informed with up-to-date information directly from the community.
Please use the instructions below to create a pin on the map. This well help keep consistent records and formatting to improve user experience.

Grass Varieties Affected by Armyworms

They can affect a wide variety of grass types, but some grasses are more vulnerable than others. Understanding how different grass varieties respond to armyworm damage can help you choose the right lawn care strategies or even select grass types that are more resilient against damage.

Zoysia grass is more resistant to fall armyworms. The green area of this golfcourse in the Southeast is the area where our blue-tag certified zoysia grass survived an aggressive armyworm infestation.

Bermuda Grass:

Susceptibility: Highly vulnerable to armyworm damage. Its dense growth can attract armyworms, and once they invade, they can quickly strip it down.

Recovery: Bermuda grass is known for its resilience, so even after an infestation, it can recover with proper treatment and care (aeration, irrigation and fertilizing)

Tall Fescue:

Susceptibility: Highly susceptible. Armyworms will feed on tall fescue lawns and can cause considerable damage.

Recovery: It’s a cool-season grass, which means it grows well in spring and fall, allowing it to recover effectively in the fall of the year if the infestation happens during warmer months of July or August. However, it will most likely require aeration, fertilization and re-seeding in the Fall especially on new sod.

Zoysia Grass:

Susceptibility: Fairly resistant. Zoysia is less preferred by armyworms due to its tougher, more fibrous nature.

Recovery: While more resistant, if affected, Zoysia grass recovers slowly compared to other varieties due to its slower growth habit. It can require additional time to fill back in from an army worm infestation.

Tips for Managing Grass Against Armyworms:

Regular Monitoring: Scout your lawn regularly for early signs of armyworm infestations, especially in more vulnerable grass types.

Resistant Varieties: If you live in an area prone to armyworm infestations, consider planting resistant varieties like zoysia grass to minimize potential damage.

How To Treat Armyworm

Is your turfgrass suffering from armyworm infestation? If possible, mow and lightly irrigate the turf prior to treating. Research has shown that insecticides are generally ineffective against large larvae, so the size of the armyworm is important to consider when selecting a treatment option. According to our friends at N.C. State Turf Files, “Pyrethroids (particularly lambda-cyhalothrin) and carbamates (carbaryl), will provide somewhat effective control against smaller larvae. Chlorantraniliprole will also control turf-feeding caterpillars, if applied very early.”

Selecting the right grass and combining it with proper maintenance can significantly reduce the long-term impact of armyworms on your lawn. Connect with the SodStar team today for help selecting the best sod for your site/lawn, and for additional resources on maintenance.