Southern Chinch Bug

Description

The southern chinch bug, Blissus insularis Barber (Hemiptera: Blissidae), is a common insect pest in turfgrass throughout Louisiana. These insects favor thick thatch, full sun exposure and hot, dry weather. They are primarily a problem in St. Augustine grass but can injure other turfgrass species. Both nymph and adult chinch bugs injure turfgrass by sucking sap from grass stems and stolons, causing turfgrass to turn yellow-brown and eventually die. Turfgrass injury most commonly occurs in the summer when weather conditions are most favorable.

Identification

In Louisiana, the southern chinch bug can complete three to four generations a year. Females begin laying eggs in late winter, with new generations appearing the following summer and fall. Depending on the temperature, an egg can mature into an adult within five to 13 weeks. Chinch bug nymphs, the adolescent stage, are black to orange in color and have a white band on the back of the body. Adults are about the size of an ant, or one-half of a centimeter. They have black bodies with white wings that form an X shape across the abdomen.

Indicators of insect presence

Nymphs and adults cause injury by sucking sap from stems and stolons.

• Injury causes grass to turn yellow, then brown and eventually die.
• Injury occurs in scattered patches that can merge together into one large dead area.

Adults can spread to new areas by crawling or flying.

Most injury occurs in hot, dry conditions in mid-to-late summer.

Flush test

Use the flush test to determine whether certain insects are present in the lawn. Mix 1 tablespoon of lemon-scented soap per 1 gallon of water. Slowly pour the soapy water onto healthy grass surrounding the injured areas. In wet conditions, drench a 1-square-foot area with soapy water. In dry conditions, drench a 4-square-foot area. Then, for five to 10 minutes, closely watch the area to see if insects come to the surface. Repeat as desired in other areas to better determine insect presence.

Cultural control practices

One way to reduce insect injury and accelerate turfgrass recovery is to maintain a healthy lawn through proper fertilization and irrigation and regular mowing. Never apply more than 1 pound of nitrogen per 1,000 square feet per application, and always follow soil test recommendations for proper fertility. Irrigate as needed while taking rainfall into account. Mow regularly, but never remove more than one-third of the leaf blade height at one mowing. Thatch can develop over time and may need to be reduced through vertical mowing. Compaction can form more quickly on finer texture soils and in areas where there is high traffic. Dethatching or aeration need to be performed in late spring to summer when the turfgrass is actively growing. Properly maintaining a lawn through these cultural practices promotes dense and vigorous turfgrass and can increase tolerance to insect injury.

Chemical control practices

In addition to cultural practices, insecticide applications may be required to achieve effective southern chinch bug control. Treat with insecticide if 25 to 30 chinch bugs per square foot are observed during the flush test. When using any insecticide, you must follow the manufacturer’s labeled directions concerning all application parameters.

For more information regarding insecticides for turfgrass insect pests, please reference the Louisiana Insect Pest Management Guide.

Download here: Louisiana Home Lawn Series: Southern Chinch Bug 3624-R