Chinch bugs are the most common insect pest that plagues St. Augustine grass. Chinch bugs most frequently appear in adult form in the spring or summer. They are slender bugs that are 1/10 to 1/5 inch long. Dark in color, they have white wings and a triangle marking in the center of their backs. Chinch bugs eat the bottoms of the tender shoots at the base of St. Augustine stems. Because their saliva is toxic to grass, these bugs cause more damage than most other bugs. Prevent chinch bug problem in St. Augustine grass by practicing proper lawn maintenance.
Identify whether chinch bugs are a problem on your St. Augustine lawn. Because chinch bug infestations look similar to fungal lawn problems and drought, the best way to identify a chinch bug problem is to look for the bugs themselves.
Mow to the proper height to prevent lawn thatch buildup. St. Augustine lawns are best mowed to a height of about 3 inches on a weekly basis. Cutting St. Augustine shorter than recommended creates conditions that harbor thatch. Thatch is a layer of dead grass and other organic material that has become entangled in the roots of the lawn. Thatch buildup provides a protective layer for the chinch bugs that eat at the tender stems of St. Augustine grass.
Hire a professional mower to perform aeration or vertical mowing on the lawn. Once thatch has built up, it needs to be removed to get rid of chinch bugs. Aeration creates a series of holes that break up thatch and allow grass roots to breathe. Vertical mowing is a more thorough procedure that hash-cuts a grass patch, disconnecting the tangles that promote thatch buildup.