Chinch bugs are common pests of St. Augustinegrass. One of your best weapons in battling this insect is good lawn management.
These little bugs like St. Augustinegrass and hot, dry weather. Periods of drought can encourage chinch bug attack. Irrigating to keep the lawn healthy but not growing excessively is one key to discourage chinch bug invasion. Recently we’ve received plenty of rain. But if we go through a dry period in summer or fall, watch for chinch bugs in St. Augustinegrass.
The kind and amount of fertilizer used also affects grass growth and chinch bug activity. Reduce grass growth rate and chinch bug problems by using minimum applications of a slow-release nitrogen fertilizer as compared to frequent doses of a water soluble nitrogen fertilizer.
Look for a fertilizer with equal amount of nitrogen and potassium and low phosphorus such as 16-2-16, 15-0-15 or 10-0-10. There are others. The main point is that the first number (nitrogen) and the third number (potassium) should be equal or close to equal. And the second number (phosphorus) should be relatively low. Fifty percent of the nitrogen should be slow-release or water-insoluble. For example, with a 16 percent nitrogen fertilizer; 8 percent should be listed as slow-release and/or water-insoluble. One to two applications of such a slow-release lawn fertilizer per year may be sufficient to produce an attractive St. Augustine lawn.
Limiting insecticide use encourages valuable beneficial insects that help battle chinch bugs. Black big-eyed bugs and earwigs are great allies. They consume large numbers of chinch bugs.
During late spring, summer and fall, inspect your St. Augustine lawn frequently for signs of chinch bug damage. As they feed, chinch bugs cause yellowish to brownish patches in the grass. Because other factors may cause similar symptoms, it’s important to identify the true case.
If you suspect chinch bug damage, part the grass in the yellowish areas and look for tiny fast-moving insects. Adult chinch bugs are about 1/8 inch long and are black with white wings. Newly hatched nymphs are about 1/20 inch long, reddish with a white band across the back. They become black as they mature.
If chinch bugs are found, start control measures promptly. Always follow the label directions before using any pesticide. Contact your UF/IFAS County Extension Office or access this link for approved insecticides http://edis/ifas.ufl.edu/lh036.
Early spot treatments can be applied while infestations are still small. Treat the off-color areas and about a 10-foot buffer zone around each. A few days later, check for effective control. If damage is widespread, the entire yard may need to be treated.