If you have a carpetgrass lawn, it’s important to know what kinds of pests you may be up against. In this guide, we’ll detail these five common carpetgrass pests, including signs of infestation, and how to get rid of and prevent these lawn invaders:
1. Mole crickets
2. White grubs
3. Nematodes
4. Armyworms
5. Sod webworms
What Is carpetgrass?
Carpetgrass, Axonopus compressus, is a warm-season grass species common in climates from East Texas to Florida, Arkansas and the Carolinas. Otherwise known as Louisiana grass or “petit gazon,” carpetgrass looks similar to centipedegrass and St. Augustinegrass, but you can tell it apart by its tall seed heads with multiple spikes.
Carpetgrass is sometimes considered a weed and treated with herbicides, but it’s also a handy turfgrass for low-fertility soils and low-maintenance yards. It‘s moderately drought-tolerant and shade-tolerant but can thrive in wet soil conditions, and it’s well-adapted to the heat and humidity and the sandy soils of Gulf Coast climates.
What 5 pests are common in carpetgrass?
Jean and Fred Hort | Flickr | CC BY 2.0
1. Mole crickets
Mole crickets are a particularly troublesome pest for all warm-season grass varieties in the Southeast, and they can do serious damage to carpetgrass lawns.
There are three varieties:
- Northern mole cricket (Neocurtilla hexadactyla)
- Southern mole cricket (Neoscapteriscus borellii)
- Tawny mole cricket (Neoscapteriscus vicinus)
The tawny mole cricket is the most dangerous to lawns, as its main diet is turfgrass roots and leaf blades. The Southern mole cricket is less destructive, but it can still cause an infestation.
To check for a mole cricket infestation, try a soapy water drench. Mix 1-2 ounces of liquid dish soap into water and pour over a plot about 2 square feet in size. The crickets should float to the surface quickly if present.
What mole crickets look like:
- Mole crickets have powerful front legs designed for digging, often resembling a mole’s.
- Northern and Southern mole crickets are both dark brown and around 1 to 1.5 inches at mature size, but the Southern mole cricket has four distinctive lighter tan spots on its head.
- Tawny mole crickets are tan all over and larger, reaching a mature size of 1.5 to 2 inches.
Signs mole crickets have invaded your lawn: Poor turf growth and loosened soil, tunneling and mound building.
How to treat mole crickets: Mole crickets tend to stay in the same area of grass, so “mapping” symptomatic regions is the best way to determine where to give your yard a targeted treatment.
A targeted treatment is better than treating the whole yard, as it is more effective and results in less pesticide use overall.
Several pesticides and chemical baits are available for mole cricket treatment, as are beneficial nematodes for a natural, non-chemical option.
How to prevent mole crickets: Pesticide application can be used as a preventive measure if you have a history of mole cricket infestation.
Several species of wasp are also natural predators of mole crickets, so planting flowers that attract garden predators can lessen their impact.
Patty O’Hearn Kickham | Flickr | CC BY 2.0
2. White grubs
The pesky critters known as “white grubs” are actually the larvae of many common scarab beetles. Carpetgrass can be affected by these and other grubs:
- Japanese beetles
- May and June beetles
- Southern masked chafers
- Green June beetles.
Most white grubs feed on the roots of turfgrass, while green June beetle grubs tunnel through soil and disrupt the root system. All grasses are susceptible to white grubs, which typically emerge in late June or early July.
What white grubs look like: White grubs vary in appearance based on variety.
- Japanese beetles: 0.1 inches long and translucent upon hatching; 1 inch at mature size with a yellowish-brown head
- Southern masked chafers: 0.12 inches long and white on hatching; turn gray after feeding; 1 inch at mature size with a dark, chestnut brown head
- May and June beetles: up to 1.25 inch at mature size; cream-colored, C-shaped bodies with three pairs of legs and a tan head
- Green June beetles: 2 inches long at mature size; short legs and stiff backs with bristles
Signs white grubs have infested your lawn: It can be difficult to notice white grub damage at first because it primarily affects turfgrass’s underground root system, and damage can be masked by rainfall or irrigation.
Plants that adult beetles commonly feed on will show damage before a white grub infestation. Infested turf will eventually wilt and turn yellow, and soil underneath the grass may feel spongy. Green June grubs may also leave mounds of soil by the tunnels they create.
How to treat white grubs: Many organic and chemical methods are available to treat white grubs. Milky spore disease and beneficial nematodes are two common natural treatments.
Pesticides with these active ingredients are labeled for white grub use:
- Imidacloprid
- Trichlorfon
- Chlorantraniliprole
- Clothianidin
How to prevent white grubs: Grubs can damage even healthy turf, but keeping your yard well-maintained can help it weather an infestation more easily. If you notice adult beetle activity in your yard, preventative chemical or biological treatments can help you avoid a future white grub infestation.
3. Nematodes
You may be familiar with beneficial nematodes, which feed on pests and are often used as an organic lawn care treatment. Their harmful cousins, however, can feed on plant roots and infect turfgrass and landscape plants.
There are a variety of plant-feeding nematodes that affect turfgrass, including
- Stinging nematodes
- Stubby-root nematodes
- Ring nematodes
Luckily, carpetgrass is resistant to root-knot nematodes, which are common throughout the Southeast and the Gulf Coast area.
What nematodes look like: Nematodes are microscopic, so you won’t be able to see them in your yard. To figure out whether you’re facing a nematode infestation, look for symptoms in your plants and soil.
Signs nematodes have infested your lawn: Wilting, slow growth that doesn’t respond to fertilizer or watering, stunted or swollen roots (also known as root galling)
How to treat nematodes: As with many other lawn pests, keeping your grass healthy can help it to sustain a nematode infestation. There are a few nematicides available for yard use, including Nortica, Nimitz Pro G, and Indemnify.
How to prevent nematodes: Nematodes are usually introduced to your yard or garden through infected soil or plants, so make your purchases from reliable nurseries and don’t move infected plants to different parts of your yard.
Also, avoid excessive nitrogen and stress conditions to prevent major damage.
4. Armyworms
Armyworms are the larvae of moths in the Spodoptera family, which are native east of the Rocky Mountains. Grass is their primary diet, so an armyworm infestation can do a number on your turfgrass, particularly for warm-season grasses like crabgrass, bermudagrass and centipede grass.
The fall armyworm, Spodoptera frugiperda, is the most harmful species for turfgrass.
What armyworms look like: Armyworm larvae range from a dark brownish-green to black, and have long stripes in white, orange, and dark brown.
At mature size they’re around 1.5 inches long, and they have mottled, yellowish-brown heads. Adult armyworm moths have white hind wings and dark gray front wings, with a wingspan of around 1.5 inches.
Signs armyworms have invaded your lawn: The main symptom of armyworms is foliage damage caused by feeding on grass leaf sheaths, which often leaves a clear “window pane” in leaf blades stripped of the top layer.
Symptoms of severe armyworm damage include loss of green color or browning in grass.
How to treat armyworms: Luckily, armyworm outbreaks in turfgrass are usually small, and often managed by natural predators.
In cases where yard damage is severe or armyworm numbers are excessive, several pesticides are available for armyworm treatment, including:
- Halofenozide
- Spinosad
- Bacillus thuringiensis (a biological pesticide that comes from bacteria and won’t affect beneficial insects)
- Bifenthrin
- Carbaryl
- Esfenvalerate
- Permethrin
How to prevent armyworms: Lawn Love has a great guide to dealing with armyworms. Preventing these invaders involves removing weeds, keeping soil moist and cool, removing thatch annually, and considering a preventive pesticide regimen if armyworms are common in your area.
5. Sod webworms
Sod webworms are moth larvae from the Pyralidae family, which has over 20 species that can harm turfgrass by feeding on its leaves. It’s most common to see webworm activity in springtime, so keep an eye out for damage in April or early May.
What sod webworms look like: Sod webworm larvae are gray or tan with small black spots and brown heads. They’re typically around three-quarters to 1 inch at mature size. Webworm moths, meanwhile, are brownish-yellow and cigar-shaped with a long snout. When fully grown, they’re around one-half to three-quarters inches.
Signs sod webworms have infested your lawn: One of the earliest symptoms of a sod webworm infestation is the presence of adult moths.
When webworm larvae start to feed on your carpetgrass, you may notice ragged brown spots in turf that look grazed or scalped, as well as fecal matter and silk webbing.
How to treat sod webworms: A healthy lawn will usually be able to outgrow webworm damage, but heavy infestations can be treated with insecticides, parasitic nematodes, and Bacillus thuringiensis.
Predator species like wasps can provide another form of biological control.
How to prevent sod webworms: Proper lawn care, including regular mowing, can help prevent sod webworms. Mow your lawn at the correct height, fertilize sparingly, and remove thatch and collect its clippings.
When to call a pro for help with carpetgrass pests
Carpetgrass is a hardy turfgrass option for difficult lawn conditions, but it’s still susceptible to pests. If you’re dealing with unwanted critters in your carpetgrass, our lawn care professionals can help.
Main Photo Credit: Forest & Kim Starr | CC BY 3.0 US | via Wikimedia Commons
