Chinch Bugs: No Easy Fix

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

Summertime in San Antonio means a lot of different things to people — grillin’, fun in the sun, barefoot walks in the lawn and other outdoor activities.

Unfortunately, the hot temperatures in July and August also have a daunting impact on local lawns and landscapes by creating water stress. When St. Augustine lawns in full sun become water stressed in July and August, 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. St. Augustine grass is a chinch bug’s favorite meal, but Bermuda and Zoysia grasses may be attacked as well.

Here are a couple of 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 to get away from the soapy water.
  • Flotation method: take a metal can with both ends removed and push one end into the ground at the border of the sick grass. Slowly fill with water and see if chinch bugs float up. Repeat for several different areas.

Once you’ve determined chinch bugs are present, you must target the infestation. To reduce chinch bug populations, 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 a) non-target beneficial insects will be adversely impacted by the treatment, and b) chinch bugs won’t be present in the entire yard.

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

Secondly, avoid over-fertilizing your grass. Too much nutrients in the soil will encourage weed growth as well as place stress on the damaged root system. Aerate the affected turf areas to allow nutrients, water and oxygen to reach the root zone and get those roots back on the road to recovery.

Picture of Nathan Riggs
Nathan Riggs
Nathan Riggs is a SAWS project coordinator and licensed irrigator who also happens to have a degree in entomology from Texas A&M University. Yes, Nathan’s a bug expert, and not just on water bugs! When he’s not hard at work on SAWS conservation projects, he enjoys a wide variety of interests including: landscaping, hiking, photography of flowers, insects and other critters, and planning his next adventure with his wife Ella and family.
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