Chinch bugs are not a cinch to get rid of

Published: Sunday, August 1, 2010 at 7:17 p.m.
Last Modified: Sunday, August 1, 2010 at 7:17 p.m.

Q: I have a chinch bug problem in my St. Augustine lawn. My lawn service company says they are treating it, but it either is not working or the treatment isn't working fast enough because I am losing more of my lawn. I don't want to resod. What should I do?

A: Chinch bugs are the most destructive pest we have in our lawns and the most difficult to control. The heat of summer really brings them out. They damage the grass by sucking the plant's juices. Normally, we first see the damage to the grass in the hottest areas of the lawn first. A clump will go from green to yellow to brown in color within about a week. If you get down on your hands and knees and look very closely at the interface of the green grass and the damaged grass, you should see small gray insects, a little smaller than a grain of rice. You can try to flush out the chinch bugs by making a bucket of very soapy water and pouring it over a couple of square feet of damaged grass. After a few minutes, the chinch bugs will crawl up the grass blades and you can get a better idea of how many insects you are dealing with.

Your pest control company probably is spraying the same product they used last year, but this year it may not be working as well. According to Dr. Eileen Buss, a UF/IFAS landscape entomologist, there are pesticide-resistant chinch bugs in localized areas of Gainesville. Chinch bugs have become resistant to Bifenthrin, a very popular turf pesticide. Bifenthrin, also called Talstar, used to be extremely effective against chinch bugs, but now the insects have developed some resistance to this pesticide. Therefore, it is important that you discuss with your lawn service company a management strategy that includes pesticide rotation, application rates and making sure that the product they use is watered in. One of the chemicals that is used in the rotation requires that the insects feed on the grass before they die. This can take up to a week, so you may see slower progress than you are used to. If your lawn service company is using the proper chemical rotation and using the right application rates, you can expect control of the chinch bugs. There currently is research going on to deal with the pesticide resistance in the chinch bugs in Florida.

You also can attempt to prevent chinch bugs from moving into your lawn by following good cultural practices. Use fertilizers that have a good portion of nitrogen in a slow-release form. Frequent applications of water soluble nitrogen fertilizers may increase chinch bug survival, development time and the number of eggs that they lay.

Also, excessive fertilizing and watering increase thatch in the lawn. If there is a heavy layer of thatch, it will be difficult to get pesticides to where they need to be.

Mowing at the correct height is another good cultural practice that will make your lawn less prone to chinch bug damage. Mow your standard St. Augustine grass at 3 to 4 inches.

For more information on dealing with chinch bugs, go to the UF/IFAS website,

Wendy Wilber is an extension agent with UF/IFAS. E-mail her at

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