Chinch Bugs in Florida Lawns: How to Spot and Stop Them

What chinch bugs are and what they do

The southern chinch bug is the most damaging insect pest of St. Augustine grass in Florida, which is the lawn grass on most Polk County properties. The adults are tiny, about a fifth of an inch long, with black bodies and white wings. The young nymphs are even smaller, and are reddish-orange with a pale band across the back. They feed on the sap of the grass, and where a lot of them gather the turf yellows, then turns brown and dies.

Because the damage looks like a dry lawn, many homeowners add water and fertilizer and make the problem worse. The first thing to do is find out whether chinch bugs are really the cause.

Chinch bug damage or drought? How to tell

Chinch bug damage usually starts in the hottest, sunniest part of the lawn, often along a driveway, a sidewalk or a south-facing edge where the ground gets the most heat. It shows up as irregular yellow patches that turn brown and slowly grow outward. A patch that keeps spreading while the rest of the lawn stays green is a warning sign.

Other problems look similar. Drought stress and a broken sprinkler head tend to follow the pattern of the spray, with edges that line up with a zone. Fungus such as gray leaf spot is more common in damp, shaded areas and leaves spots on the blades. A useful clue is that drought-stressed grass perks up after a good watering, while grass killed by chinch bugs does not. These are common patterns, not certainties, so confirm with the test below before you spend money on a treatment.

The coffee can test

Cut both ends out of a metal can, such as a large coffee can. Push it two to three inches into the soil at the edge of the damaged area, where yellow turf meets green, since that is where the insects are feeding. Fill the can with water and keep it topped up for five to ten minutes. If chinch bugs are present, they float to the surface, where you can see the reddish nymphs and the black adults.

Do the test in a few spots around the edge of the damage, not only one. Finding none does not rule them out, but finding them gives you a clear answer, and it tells you where to treat.

When chinch bugs show up in Polk County

Chinch bugs are most active in hot weather, and in Central Florida that means from late spring through the end of summer, with the worst damage usually in the heat of July through September. Sandy ridge soil in places like Haines City and Lake Wales heats and dries quickly, and lawns beside pavement in Lakeland, Winter Haven and Bartow are common starting points. In our warm climate they can stay active longer than in cooler states, so check the lawn whenever a patch appears, not only in summer.

How to treat an infestation

If the test finds chinch bugs, treat the damaged area and a margin of healthy grass around it, since the insects move outward from the patch into green turf. Follow the product label for the rate, for whether to water the product in, and for keeping it away from lakes, ponds and drains, which matters in a county with so many lakefront yards.

Insecticide choice matters because chinch bugs in Florida have developed resistance to some products. Seasonal cover sprays of the same type of insecticide, applied again and again whether or not bugs are present, have helped create that problem. University of Florida Extension guidance has moved toward thorough applications of systemic products when treatment is needed. Because product recommendations change, check the current guidance with the UF/IFAS Extension office in Polk County before you buy, or ask the company you hire exactly what it uses and why.

How to prevent chinch bug damage

Mow St. Augustine grass at three to four inches. Taller grass has deeper roots and shades the soil, and it tolerates chinch bug feeding better than turf that has been cut short. Avoid heavy nitrogen feeding and a thick layer of thatch, both of which make a lawn more attractive to the insects. Polk County's ordinance restricts fertilizer near water and before heavy rain; some cities and nearby counties add a summer ban, so check your city.

Water properly within the watering days that apply to your address. Under a one-day-a-week limit, an even sprinkler system matters more, because a dry strip beside the driveway is exactly where chinch bugs start. Some St. Augustine varieties, including Floralawn and Floratine, offer some resistance to chinch bug feeding, so ask about them if you are replacing a lawn, though no variety is immune. Floratam was released with chinch bug resistance, but UF/IFAS says that resistance has largely been lost.

Fixing the dead patches

Grass that has died will not grow back. Once the insects are under control, replace dead patches with new sod or plugs, and keep the new grass watered within the rules. If the same spot dies every summer, look at the cause beneath the pest, which is often poor irrigation coverage, compacted soil or too much heat from pavement, and fix that first.

When to hire a pro

Call in a lawn care company if the patches are spreading fast, the lawn is large or the problem keeps returning. Ask whether they confirm chinch bugs with a test before they treat, which products they use and whether they rotate them, how they handle the area near water, and what they do if the problem returns. A crew that sprays on a calendar without checking is the practice that has led to resistance.