Southern Chinch Bugs Vol. 9, No. 17
Your Extension Experts
September 5, 1997
July 25, 1997
June 23, 1997
May 12, 1997
March 17, 1997
There’s a big patch of dead grass in the middle of the yard and it is getting bigger by the week. What is causing this problem? If this is a St. Augustine lawn, chinch bugs may be the culprits, but don’t start treating until you are sure. Chinch bugs are the most important insect pests of St. Augustinegrass, but there are several diseases that cause similar symptoms, and insecticides will not control disease problems.
Check for chinch bugs by getting down on your knees and using your fingers to dig through leaves, stems, and thatch at the edge of the dying grass—where the grass is still green or just beginning to yellow. Better yet, take a one-gallon metal can that has had the bottom cut out, or a large diameter piece of PVC pipe, force it into the turf, fill it with water, and check for floating chinch bugs. Look carefully, these are small insects. But it takes 20+ chinch bugs per square foot to kill grass, so chinch bugs should be relatively easy to find if they are the cause of the problem.
Chinch bug outbreaks are more likely during periods of hot, dry weather, and St Augustinegrass growing in full sun is more susceptible than St. Augustinegrass that receives some shade. Adult chinch bugs are about 1/8 to 3/16 inch long and dark-colored with white wings crossed over their back. Young nymphs are red or pink-colored, but older nymphs are dark-colored, like adults, but without wings. Both nymphs and adults feed on stems and stolons with piercing-sucking mouthparts, and it is the toxic saliva they inject while feeding that injures or kills the grass. Although chinch bugs are primarily pests of St. Augustine lawns, they sometimes damage Zoysia and other turfgrasses.
Although they look alike, southern chinch bug, Blissus insularis, is a different species than common chinch bug, Blissus leucopterus leucopterus, which is an important pest of corn and other grain crops, such as wheat and oats. Hairy chinch bug, Blissus leucopterus hirtus, is an important pest of northern turfgrasses. There’s also false chinch bug, Nysius raphanus, which is similar in size but different in appearance when viewed closeup and feeds primarily on weeds and non-crop grasses.
Control: If it is dry, water the grass the day before treating; this forces the bugs to move closer to the surface where the insecticide can reach them more readily. Then spray with a lawn insecticide containing an active ingredient such as bifenthrin, cyfluthrin, lambda-cyhalothrin, or permethrin using a hose-end sprayer or some type of broadcast sprayer. Finish by watering lightly after treatment, no more than 1/8 to ¼ inch, to wash the spray into the thatch area where the chinch bugs are most active. Don’t water too heavily or you will wash the insecticide past the bugs. For best control of heavy infestations apply a second treatment two weeks later. Granular insecticides are also an option but be sure to water in according to label directions. Products that contain clothianidin (Arena) will control chinch bugs that are resistant to the pyrethroid insecticides listed above.
See page 5 of Extension Publication 2331, Control Insect Pests in and around the Home Lawn
for more information:
For information on chinch bug control in commercial turf, see page 5 and 6 of Extension Publication 1858, Insect Control in Commercial Turf.
Blake Layton, Extension Entomology Specialist, Mississippi State University Extension Service.
The information given here is for educational purposes only. Always read and follow current label directions. Specific commercial products are mentioned as examples only and reference to specific products or trade names is made with the understanding that no discrimination is intended to other products that may also be suitable and appropriately labeled.
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