With the hot days of summer, you should be on the lookout for chinch bugs in your lawn, especially in St. Augustine grass. These pests cause extensive damage very quickly, including killing St. Augustine turf, during the hot days of July, August and well into September. Chinch bugs like hot, dry, sunny lawns; hence, shady lawns are not usually infested. Lawns suffering from chinch bug infestation show large patches of irregular, yellowish, stunted, wilted grass. Chinch bugs suck the sap from grass blades, at the same time injuring the grass, causing it to wither and die, leaving brown areas of turf.
Unlike turf killed by grub worms, grass killed by chinch bugs remains attached to its roots. To check for chinch bugs, push a bottomless can into the ground near the edge of a dead patch of lawn and fill it with water. If chinch bugs are present, they will float to the surface within a few minutes. Look for fast moving bugs approximately 3/16 to 1/8 inch in length with black bodies and white wings. Younger, smaller nymphs may be orange-pink in color with a white band across their back. Insecticides to control chinch bugs include dursban and diazinon. Water the lawn thoroughly to bring the bugs to the surface before applying insecticide according to the product directions.
Tom Russell, Smith County Master Gardener
Texas Cooperative Extension
Have you ever examined your lawn after watering and found dry, wilted looking areas and assumed that your sprinkler did not cover the area well? You add more water and it still does not respond? Chances are that you have chinch bugs.
Chinch bugs are small black insects 1/8th to 1/4th inch long, with white wings and the appearance of a white diamond on their backs. They attack St. Augustine lawns primarily. The symptoms are similar to water stress: the turf looks dry but fails to respond to watering. It normally starts in small patches in the hottest parts of the lawn, especially near sidewalks, curbs, and driveways. Damage can sometimes be confused with brown patch, but brown patch appears in unique semi-circular patterns, whereas chinch bug damage appears in irregular patches. Furthermore, brown patch usually occurs later in the growing season, but chinch bugs are active in the hot summer months. If there are enough chinch bugs present in your lawn to cause damage, you can part the grass along the edge of an infected area and see the bugs with the naked eye. Another detection method is to cut both ends out of a three-pound coffee can and push it into the lawn along the edge of a suspected area ! and fill it with water. If it is chinch bugs, a large number should float to the surface of the water.
When chinch bug damage is visible, a variety of liquid and granular insecticides can be used to prevent further damage. Look for brands that contain bendiocarb, cyfluthrin, carbaryl, isofenphos, or permethrin. After application, inspect the lawn every three to five days for two weeks to ensure that the insects are under control. Spot spray where needed. Also some biological controls have been tested, but none has proven to be very effective once damage has occurred.
Chinch bugs may be controlled somewhat by appropriate watering, lawn feeding, and thatch control. Thatch control is very important, as thatch provides a protective home for chinch bugs. The best thatch control is proper mowing. Do not remove more than 30% to 40% of the grass leaves, and use a mulching mower. These grass clippings will break down rapidly and not contribute to thatch. Cutting less frequently results in more and larger clippings that are slow to break down and can contribute to a thatch build up.
Bob Ellis, Smith County Master Gardener
Texas Cooperative Extension
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