Types of Insect Leaf Damage in Lawns And How to Treat It

Every homeowner strives to maintain a lush green lawn.

However, when an insect infestation occurs, it can turn a flourishing turf into unsightly patches of brown chewed-up wreckage. While the situation is disheartening, all is not lost. You can take strategic steps to restore your lawn’s health.

In this post, we’ll help you identify the insects causing the damage and provide solutions to treat each of them effectively.

Chinch Bugs (Blissus leucopterus)

Chinch bugs are common lawn pests associated with sunny dry conditions — *Chinch bugs are common lawn pests associated with sunny, dry conditions. Image: psu.edu*

The chinch bugs are a common pest in many lawn grasses including the fescues and ryegrass. When small, they resemble nymphs and are only ⅕ inch long in maturity.

In their nymph stage, they are black with orange or red markings but no wings while the adult bugs are black with white markings on their wings.

Recognizing the Problem

The bugs pierce the leaf blades and create a straw-like tube where they suck out the juices. Due to the damage, the leaves turn yellow and then brown.

Management

The chinch bugs are mostly active in dry and sunny conditions, particularly in the summer. Raising mowing height, deep, weekly watering, and fertilizing your lawn can help limit clinch bug damage.

If you prefer a more natural treatment, allow natural predators like ground beetles or ‘big-eyed bugs to feed on the clinch bugs.

Chemical insecticides such as bifenthrin, trichlorfon, or cyfluthrin can also provide effective control against clinch bugs. An application from April to mid-June is recommended. However, use chemical treatments sparingly as they may harm the natural clinch bug predators and other soil microorganisms.

Sod Webworm (Herpetogramma licarsisalis)

*Sod webworm is the caterpillar of the lawn moth and it chews the grass down to the crown. Image: purdue.edu*

A sod webworm is a caterpillar of various lawn moths. It’s thick, pale green-brown, about 25mm long, with four parallel rows of brown spots on the abdomen. It chews grass blades down to the crown. Bluegrasses are particularly vulnerable to sod webworms.

Recognizing the Problem

Damage by sod webworms appears as small brown patches of grass blades that look clipped or scalped. As the damage increases, the small patches form larger irregular areas.

Green fecal pellets in the thatch, moths flying in a zigzag manner around the lawn area, or flocks of birds on your lawn may also be indicators of the infestation.

Management

Aerate and dethatch your lawn to reduce the habitat for the larvae. You can also apply granular or liquid products containing permethrin, bifenthrin, and carbaryl. Mow the grass before application and ensure other weeds are not flowering to avoid killing pollinator insects.

ArmyWorm (Spodoptera mauritia)

*Armyworm feeding on bermudagrass foliage. Image: tamu.edu*

Armyworms are serious pests of various turfs like fescues, bermudagrass, bluegrass, bentgrass, and ryegrass. The caterpillars can be green, black, or brown with white and yellow stripes, on their backs, and about 40mm in length.

Since they feed in large armies, they can strip grass blades rapidly, often causing sudden and extensive thinning of the lawn.

Recognizing the Problem

Damage by armyworms is easy to identify as they eat all the foliage, leaving only the stems and a brown-patched, scalped lawn. You can also observe them feeding in the early mornings and the late afternoons.

Management

Since armyworm infestations move quickly and require a fast response, we recommend treating with a lawn insecticide containing permethrin, spinosad, bifenthrin, or chlorantraniliprole for high-value turf grass.

Cutworm (Agrotis ipsilon)

*Cutworms cut the grass and pull into burrows beneath the soil, leaving round spots of damage on the lawn. Image: purdue.edu*

Cutworm is a caterpillar pest of the brown moth and is typically green, brown, greyish, or yellow. They are identified by their dark-colored bodies with black spots on the back and sides.

These pests burrow in the ground during the day and emerge at night to cut off the leaves at the crown level and drag them down the burrow to feed, hence the name.

Recognizing the Problem

The damage typically appears as round spots or ball marks in the soil that expand to larger areas and wilted or dead grass. You may also find the pests near the base of the cut leaves and stems.

Management

Laying a wet hessian or potato sack bag on the affected area is a popular natural strategy used to eliminate small infestations. They are attracted to the dark and damp bag, making it a viable solution for removing cutworms from a lawn.

For larger infestations, apply an insecticide product containing cyfluthrin, clothianidin, bifenthrin, acephate, and carbaryl.

Ensure that you read the label as the product may require prior mowing or afternoon applications for the best results.

Sylvia Kiragu

Lead Editor for Insight Weeds.