Inspect Your Lawn This Summer for Chinch Bugs

A client called me to come look at a section of her St. Augustine lawn. Apparently, it was turning brown and spreading. Upon inspection I did notice some lesions I thought appeared to be gray leaf spot. After making several slides, I was unsuccessful in finding the disease under the microscope. The next morning, I noticed some tiny bugs crawling around in the sample and one on my desk. I immediately picked them up, placed them in  a container and put them under the compound microscope. After several attempts to flip  them on their legs, I was able to see what looked like a stage 5 nymph chinch bug. A few  moments later I got a text from a landscape professional with pictures of a lawn damaged by chinch bugs.

Hot, dry weather tends to bring chinch bugs to the feeding table-your lawn.  Chinch bugs are pests of St. Augustine grass, and can be found throughout the state.   However, chinch bugs have been known to feed on Zoysia, Bermuda, Bahia, and Centipede grasses. As young nymphs, chinch bugs are bright red with a white band around their abdomen.  Older nymphs progress from orange-brown to gray and finally black.  As adults, they are about 1/5-inch long and light in color with small black triangular patches on the wings.  The wings are carried folded over their back.

Chinch bug infestation and damage are noticed during hot dry periods in sunny areas of the lawn.  Chinch bugs suck the juices from the blades of grass resulting in the grass turning yellow and eventually brown.  Injury appears as spreading patches of brown, dead grass.

If you think that chinch bugs have invaded your lawn, a common method to verify this and check population levels would be the flotation technique.  Push a coffee can, with its ends cut away, two to three inches down into the lawn in a suspected area of the chinch bug infestation.  Fill the can with water and keep it full for about five to seven minutes.  All stages of chinch bugs if any will float to the top.  A threshold of 20 to 25 chinch bugs per square foot can cause damage.  Repeat this technique in several areas in the lawn.

If you find yourself having to apply an insecticide for chinch bugs, bifenthrin is a good choice.  Check the label for recommendation. Apply as a course spray in 4 – 5 gal water/ 1,000 square feet for good coverage and repeat as needed.  Irrigation of lawn prior to application will give better control. Cyfluthrin (Bayer Advanced Lawn and Garden) can be used at 3.0 ounces/gal of water for every 1,000 square feet of turf.  Read labels carefully and follow directions when applying chemicals.