If you’re watering your lawn, but those brown patches don’t seem to get any greener, you might be dealing with a common summer pest. But how can you tell the difference between damage from pests, drought, and lawn disease? Learn how to identify, remove, and prevent three of the most common summer lawn pests.
Armyworms are caterpillar-like larvae of fuzzy brown moths. There are several species, all striped and ranging in color from brown to yellow, red, and green. They’re typically one to two inches long.
Like many insects, armyworms have four life stages: egg, larvae, pupa, and adult. There are three generations:
First generation: April-May
Second generation: June-July
Third generation: August-September
Armyworms are most destructive in the larval stage, which is when they strip away and eat your grass stems and blades. They might also eat leaves of ornamentals or vegetables.
By the time armyworms have infested, it’s usually too late to control the damage. If you suspect an invasion, look for:
Circular bare patches
Brown patches surrounded by healthy turf
Transparent-looking grass blades
More birds feeding on your lawn than usual
Armyworms typically attack Kentucky bluegrass, tall fescue, fine fescue, Bermudagrass, and ryegrass. They are particularly prominent in the South. Most armyworms are spotted in lawns in late summer, but outbreaks have been reported as early as April.
See if armyworms are infesting your lawn with a simple soap flush test. Mix three tablespoons of dish soap and one gallon of water. Pour over any patches that appear infected. Within a few minutes, larvae should rise to the surface.
Do the test at night when they are most active. If there are more than three armyworms per square foot, it’s time to take action.
Get rid of armyworms with one of two organic methods:
Nematodes are an organic option, which can help get rid of more than 200 kinds of turf pests. These microscopic worms release toxins which kill the insects. Species that specifically target armyworms include Steinernema carpocapsae, Heterorhabditis bacteriophora, and Heterorhabditis indica.
Bacillus thuringiensis (Bt) is another organic pest control method. Bt is a microbe that makes toxic proteins that target insect larvae. It doesn’t harm the environment because it naturally occurs in the soil.
Armyworms are attracted to yards that have overgrown grass and weeds. Prevent them by:
Keeping your lawn watered
Keeping the grass short
Checking monthly for armyworms
Using preventative pesticides
Armyworms have some natural predators, like flies, ground beetles, skunks, and birds. Try attracting more birds to your yard and see if that helps.
Sod webworms are little caterpillars that build silky tunnels in your lawn to hibernate through the winter. They are the larvae of more than 20 species of close-winged moths. Larvae are brown and green, with brown heads and dark spots.
Watch for sod webworms in their larvae stage, when they’re around an inch long. This is when they’ll cause the most turf damage.
There are three generations:
First generation: May-June
Second generation: July-August
Third generation: September
Sod webworms can quickly damage turf. They eat grass, particularly the stems and leaves. They’re attracted to lawns with abundant thatch, especially in dry, warm weather, which is why they’re more common in the South.
Damage caused by sod webworms can often be confused for dormant grass or drought stress. If you think you might have an infestation, look for:
Shortened patches of grass
Webworm feces (tiny green pellets)
To test, combine ¼ cup of household detergent with two gallons of water. Pour over a three-foot patch of damaged lawn. If your lawn is infested, the webworms should appear at the surface within 10 minutes. If you count more than 15 sod webworms, take action.
The most recommended natural method for dealing with sod webworms is to use parasitic nematodes, like Steinerenema. Pesticides are not recommended because they often kill other beneficial insects. Try not to use chemical pesticides unless you count more than 15 sod webworms per square yard. For a serious infestation, use insecticides that contain bifenthrin.
Mole crickets aren’t the prettiest pests. Adults are one to two inches long, with six legs, long antennae, and a pair of wings. Mole crickets dig tunnels under your lawn, disrupting the growing grass. They feast on the roots and leaves, causing drought-like symptoms and patches of brown, dying grass.
Mole crickets cause the most damage between February and June, and during September and October. They can be active year-round in hot regions like Florida.
Look out for:
Irregular brown patches
Mounds of dirt striping your lawn (from tunneling)
Weak grass roots
Grass pulling up from the ground easily
To see if mole crickets are to blame, use a dish soap test. Mix one gallon of water with one to two ounces of dish soap. Locate about two square feet of your yard that seems infested. Pour the mixture over this area and wait to see if any mole crickets emerge.
The best natural control method for mole crickets is nematodes. There are also chemical options like baits and insecticides containing:
Mole crickets tend to target lawns in the Southeast. They’re less commonly found in Bermudagrass and fine fescue, so consider these grasses if they grow in your region and mole crickets are a problem.