How to Identify and Control Chinch Bugs

Many homeowners aspire to maintain the perfect lawn, but there are certain pests that can make this dream rather challenging.

Chinch bugs are a family of 20 species native to North America. Out of this group, only a handful cause significant damage to turf grass. These bugs eat a variety of grasses including ryegrass, Kentucky bluegrass, fescues, and creeping bentgrass. In addition to ornamental grasses, chinch bugs can also impact cultivated grasses like corn and sorghum and occasionally wheat and barley. Broadleaf plants are not affected. 

Let’s cover the most damaging of the Blissus genus, the common chinch bug (Blissus leucopterus leucopterus), the hairy chinch bug (Blissus leucopterus hirtus), the southern chinch bug (Blissus insularis Barber) and the western chinch bug (Blissus occiduus Barber). You’ll learn how to identify their damage and how to prevent it.

What Are Chinch Bugs?

Chinch bugs are a family of insects with piercing and sucking mouthparts that feed on grasses. They can be found as north as Main and as west as Minnesota.

Adults have small, oblong bodies and undergo several nymph stages before reaching adulthood. Activity is highest in the summer and after drought periods. They also release a characteristic musty scent when crushed. 

Types Of Chinch Bugs

True or common chinch bug (Blissus leucopterus leucopterus) is the most geographically far-reaching species. It is found from southern Canada down to most of the eastern U.S. and west to the Rocky Mountains. This species does not typically overlap with the southern species. 

In the northeast of the U.S., the most common species is the hairy chinch bug (Blissus leucopterus hirtus). Hairy chinch bugs prefer to feed on ryegrass and fescues but will also attack other types of lawn grass. Adults are around ⅕ inches long with black and white markings on their wings and red legs.

As their name suggests, hairy chinch bugs are covered in fine hairs. The nymphs are wingless and typically have red and orange markings. 

The southern chinch bug (Blissus insularis Barber) is the most common species in the Southeast and can be found as far west as Texas. Southern chinch bug adults can be mistaken for big-eyed bugs, but southern chinch bugs have shiny white wings.

Nymphs gradually change colors as they undergo different developmental stages, starting with orange bodies with a white band across their middle to eventually developing black bodies with white wings. The southern chinch bug especially prefers St. Augustine grass and also Bermuda grass, centipede grass, and zoysia grass.

The western chinch bug (Blissus occiduus Barbe)r is a series pest of the buffalo grasses, Buchloë dactyloides (Nuttall) Engelmann, zoysia grasses, and Zoysia japonica Steudel, commonly used as turf grass in the midwest. 

Life Cycle

Adult bugs overwinter in plant debris, dead plant matter, near the foundations of structures and in other protected areas near their infestation site. They leave their overwintering sites in the spring when daytime temperatures are above 70°F (21°C) for several consecutive days, mate, and start to lay eggs.

The eggs are deposited near protected areas of the plant such as in the crown of grasses, thatch, and on the lower sheaf of bottom leaves. Females are prolific and can lay hundreds of eggs in a few short weeks.

The eggs are initially white in color and gradually turn orange one to two weeks before hatching. Nymphs typically undergo five molts before maturity. They develop their wings during the fourth and fifth instar. In cool weather, nymphs may undergo an additional instar. 

Different species have different numbers of generations per year. In the north, the hairy chinch bug may have two to three generations whereas the southern chinch bug may have seven to nine generations. Generally, chinch bugs thrive under warm weather conditions. In parts of the south, chinch bugs do not overwinter at all and continuously reproduce throughout the year. 

Chinch Bug Damage

Chinch bugs are difficult to spot because their bodies are well hidden under grasses. Diagnosing the issue is difficult because the damage looks similar to drought damage or other lawn diseases. However, there are a few ways to spot the difference. 

Symptoms

Chinch bugs use tube-like piercing mouthparts to feed on the sap of grass blades. During the feeding process, the bugs also inject a toxic substance into the plant tissue which causes yellowing and plant death.

Initially, irregular yellow patches might appear on your lawn which gradually expand as the pest pressure increases. Plants like clover or broadleaf weeds on the lawn will appear unaffected.

Check healthy grass near the edge of the affected patch for signs. Since these bugs are visible to the naked eye, you should be able to find them in the thatches in late summer if you spread the grass blades apart.

Alternatively, you can use the tin can method. Take a large tin or a large bottle and cut off both ends. Insert one end about 1-2 inches into the soil surface and fill the exposed part of the can with a few inches of water. Use your hand to agitate the water. After about 10 minutes, bugs and other inserts will float to the surface from the combination of the agitation and their need to breathe.

You may see big-eyed bugs also in this sample. These are beneficial and natural predators of chinch bugs. If more than half of your sample is big-eyed bugs, their population might be sufficient to naturally control a chinch bug infestation. 

What If It’s Not Chinch Bugs?

Heat and drought stress can cause dead patches in the lawn. These patches are usually large and may even be the entire lawn. The grass should bounce back quickly after deep watering. However, lawns affected by bugs will not be as resilient. 

The quality of your soil also can impact the look of your lawn. Patches of dead grass can appear in your lawn if the pH of the soil is too high. Improper fertilization will also cause your lawn to change color. If the soil does not have enough nutrients, the grass is likely to be a pale green color. If grass is over-fertilized, it might burn and turn brown. Excess nitrogen can also attract more unwanted insects to your lawn. You can get your soil tested through an at-home testing kit or by sending a sample to your local extension office.

Brown and dead spots on a lawn can also be from the development of thick thatch, or a dead layer of plant material. Thatch can develop from heavy foot traffic that damages grass. A thick thatch layer can prevent water and nutrients from reaching even the shallow root systems of turf grasses. Thatch is a good hiding place for bugs and should be managed as part of pest control and general maintenance of healthy turf. 

Control

Chinch bugs have natural enemies within the ecosystem. This includes the big-eyed bug, which is an aggressive predator, and the naturally occurring fungus Beauvaria bassiana. This fungus grows in early spring, under cool and wet conditions, and impacts all life stages of this insect. It might attack them enough early in the season to reduce their overall population during the summer.

Many chemical insecticides are detrimental to both pests and beneficial insects. The big eye bug is very sensitive to insecticides so chemical controls may have an adverse effect on the overall chinch bug population. 

Insecticidal treatment is recommended if chinch bug infestations reach a rate of 20-25 bugs per square foot or 15 per tin can method. However, this level of infestation is rare. If needed, follow the usage and safety instructions carefully and apply the right insecticides. Sprays must come in contact with the bugs in order to kill them so a single application.

Prevention

We recommend integrated pest management to prevent and control infestations.

Lawns that are well-watered and receive proper fertilization are better protected. As with many other pests, these bugs are attracted to plants already under stress.

There are some cultivars of grasses that are more susceptible to chinch bugs than others. For example, the ‘Raleigh’ variety of St. Augustine grass is highly susceptible whereas ‘Floratam’ and ‘Floralawn’ have some resistance.

In general, turf grasses and tall fescue infected with non-pathogenic intercellular fungi or endophytes are more resistant. You can reseed damaged grass areas with endophyte-enhanced turfs as a method of cultural control. 

Frequently Asked Questions