If your lawn looked healthy a few days ago but suddenly has large areas that appear brown, thin, or almost scalped, don’t automatically assume the late-summer heat is to blame.
Fall armyworms could be the culprit.
That’s especially worth checking right now. Clemson Cooperative Extension’s South Carolina Pest Tracker currently lists fall armyworms as its “Current Focus,” describing them as a serious turfgrass pest capable of causing significant damage in a short period of time.
For homeowners in Columbia, Lexington, West Columbia, Chapin, Irmo, and throughout the Midlands, knowing what armyworm damage looks like – and checking a suspicious lawn quickly – can make a big difference.
Despite the name, the critter that damages your lawn isn’t actually a worm. Fall armyworms are caterpillars, the larval stage of a moth.
The adult moths don’t feed on your grass. It’s the caterpillars that cause the damage by eating turfgrass leaf blades. Clemson notes that fall armyworms migrate north each year from warmer areas where they can survive the winter, and populations can vary considerably from year to year.
They can also have multiple generations in a season. In South Carolina, Clemson has documented activity continuing into November when temperatures remain mild.
That makes late summer and early fall an important time to pay attention to sudden changes in your lawn.
One of the biggest clues is how quickly the lawn changes.
Fall armyworms feed on the grass blades above ground. With a significant infestation, a lawn can go from looking healthy to severely thinned or brown remarkably quickly.
You may notice:
The important word here is suddenly.
A lawn that gradually loses color during prolonged hot, dry weather tells us something different from turf that appears to be disappearing over the course of several days.
This is where homeowners can easily get fooled.
Both drought stress and armyworm feeding can leave a lawn looking brown.
In fact, Clemson recommends checking areas that look drought-stressed when scouting for armyworms.
So don’t diagnose the problem based on color alone.
Look closer.
If the lawn has received adequate water but continues deteriorating rapidly, examine the grass blades for feeding damage and look for caterpillars. Clemson has documented armyworm-infested lawns turning brown despite receiving substantial rainfall.
That’s a good rule for lawn problems in general:
Brown grass is a symptom. It isn’t a diagnosis.
Drought, irrigation problems, disease, insects, soil conditions, and other stresses can sometimes produce similar-looking symptoms. Identifying the cause matters before deciding how to treat it.
This is one of the most useful things a homeowner can do.
Start by looking closely around the edge of a damaged area where it meets turf that still looks healthy.
Armyworms may be easier to spot during the early morning or late evening when they’re actively feeding. Birds or wasps suddenly spending a lot of time in one section of the lawn can also be a clue that there’s insect activity worth investigating.
Can’t find anything?
Clemson recommends a simple soap-flush test.
Mix approximately 1–2 tablespoons of dish detergent with 1–2 gallons of water and slowly pour it over roughly one square yard of healthy-looking turf immediately beside the damaged area.
If armyworms are present, the soapy solution irritates them and causes them to move to the surface, where they’re much easier to see. They should begin emerging within several minutes.
This isn’t a treatment for the infestation. It’s a diagnostic tool to help determine whether caterpillars are actually present.
If you find caterpillars, don’t assume every caterpillar in the lawn is a fall armyworm.
One of the most useful identifying characteristics is an inverted Y-shaped marking on the head. Armyworm larvae can reach approximately 1½ inches long.
Look for the Y marking on the head rather than trying to identify the insect by color alone.
Clemson Cooperative Extension maintains a Fall Armyworm Tracker showing activity reported across South Carolina.
View Clemson’s South Carolina Fall Armyworm Tracker
That’s particularly useful during late summer and fall because armyworm pressure isn’t identical every year or in every location. Clemson specifically notes that populations fluctuate based on weather and migration patterns.
Fall armyworms can feed on multiple turfgrass species.
That doesn’t mean a centipede, zoysia, or other lawn should be ignored.
Rather than relying only on grass type, pay attention to how quickly the turf is changing and whether there are signs of active feeding.
Here’s some good news for homeowners with established warm-season turf.
Although armyworm damage can look devastating, fall armyworms feed on the leaf blades without destroying the stolons and rhizomes of established warm-season grasses. As a result, an established warm-season lawn can survive even severe-looking feeding damage.
That doesn’t mean the lawn will immediately look normal again.
Late-season damage creates an additional challenge because Bermuda and other warm-season grasses are approaching winter dormancy. There may simply not be enough growing season remaining for the lawn to completely restore its appearance before temperatures fall.
So if armyworms damage a lawn in September, resist the urge to throw everything possible at the grass trying to force an instant recovery.
Sometimes the right answer is control the active pest, maintain the lawn appropriately, and give healthy established turf time to recover when active growth resumes.
This is an important one.
A severely damaged lawn can make homeowners think:
I need to feed this grass so it’ll grow back.
But late in the season, that’s not necessarily appropriate.
That’s another reason diagnosing lawn problems correctly matters.
More fertilizer isn’t automatically the answer to damaged or discolored grass.
If you’ve confirmed armyworms are actively feeding, time matters.
Early detection is significant because damage can occur quickly. Treatment should target the caterpillar stage—the stage actually feeding on the turf—rather than the adult moth.
The appropriate treatment depends on factors including the pest’s life stage, severity of the infestation, turf conditions, and the insecticide being used.
At Sprout Tech Turf Solutions, lawn insect control starts with figuring out what’s actually causing the damage. A brown lawn doesn’t automatically get an insecticide simply because insects are active in the area.
This deserves a nuanced answer.
Homeowners may assume that if armyworms are a seasonal threat, they should simply spray the lawn preventatively.
That makes scouting and early detection especially important.
During periods of reported armyworm activity:
The sooner you know what you’re dealing with, the sooner you can make an informed treatment decision.
Armyworms are a perfect example of why diagnosing a turf problem matters.
A lawn can look drought-stressed when the real problem is hundreds of caterpillars feeding on the grass blades. Conversely, a brown lawn can genuinely be suffering from drought, disease, irrigation issues, or another problem that an insecticide won’t solve.
If your lawn in Columbia, Lexington, West Columbia, Chapin, Irmo, or the surrounding South Carolina Midlands suddenly looks brown, thin, or chewed, take a closer look.
And if you’re not sure what you’re seeing, Sprout Tech Turf Solutions can help identify what’s causing the damage and determine the appropriate next step.
When lawn damage happens fast, figuring out why should happen fast, too.
