Chinch Bugs: Your Lawn’s Worst Enemy

Nathan Riggs

The heat and high temps of late summer aren’t the only culprits that take a toll on your landscape. If your St. Augustine lawn is looking sad and jaundiced, it may be under attack.

The calendar may indicate fall is near, but hot summer temperatures continue to linger. And, that can create water stress for local lawns and landscapes.

When lawns that get full sun exposure become water stressed in late summer, they fall victim to attack by the southern chinch bug (Blissus insularis). Chinch bugs suck the sap from the grass at the point where the blade emerges from the runner, or rhizome. As they feed on the sap, chinch bugs release saliva into the wound, causing the grass to turn yellow and die. This yellowing usually begins at a central point and radiates in a circular pattern outward as the chinch bugs expand their feeding area.

While Bermuda and Zoysia grasses are included on the chinch bug menu, they are mere appetizers compared to their favorite entrée: St. Augustine grass. Chinch bugs can reduce a beautiful St. Augustine lawn to a brown and yellow patchwork in just a few days.

There are some ways to test for chinch bugs in the affected area:

  • Drench method: flood an area on the edge of the sick grass with a soapy solution (2 tablespoons of liquid soap to 1 gallon water). If chinch bugs are present, they will emerge from the grass.
  • Flotation method: take a metal (coffee or food) can with both ends removed and push one end into the ground at the border of the sick grass. Slowly fill with soapy water and see if chinch bugs float up. Repeat for several different areas.

Once you’ve determined chinch bugs are present, you can target the infestation. Treat a 15-foot radius around the damaged area with a liquid insecticide approved for turf grasses. It IS NOT NECESSARY to treat the entire yard because non-target beneficial insects will be adversely impacted by the treatment, and the chinch bug infestations tend not to be widespread.

After treatment, you must PATIENTLY rehab the affected turf areas. Do not overwater your grass in an effort to get it back to health. Instead, water thoroughly, but infrequently to encourage a deeper, more drought-tolerant root system.

Secondly, avoid over-fertilizing your grass. Too many nutrients in the soil will encourage weed growth as well as put stress on the damaged root system. Aerate the affected turf areas to allow nutrients, water and oxygen to reach the root zone.

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