As small as they are, chinch bugs can do widespread damage to your lawn by leaving mottled brownish-yellowish patches in otherwise healthy grass. These 1/4-inch, black and white insects are particularly common in the south, where they thrive in sunny, dry sections of the lawn. Because they work fast, it’s important to take action as soon as you notice them.
Assessing the Damage
Chinch bug damage closely resembles drought damage, so before you treat for these insects, make sure they’re really the cause of your problem. Like drought damage, chinch bug damage occurs where the grass becomes hot and dry, usually during July through September.
Whereas drought damage leaves an evenly brown area, chinch bugs leave mottled yellow or brown patches with clumps of undamaged grass between. The damage often shows up around the edges of the lawn, particularly along building foundations, driveways, and other surfaces that emit heat.
Visually inspect the grass for chinch bugs and their nymphs, which are bright red with a white stripe. Slowly slide your foot over the grass to see if any chinch bugs crawl over your shoe or part the grass with your fingers and look for the bugs near the grass roots.
If you find these insects or nymphs, you can assess the degree of infestation using coffee cans. Cut the bottom off two coffee cans and push them 2 inches into the soil where you suspect the chinch bugs are. Fill the cans with water and wait 10 minutes, allowing the chinch bugs to float to the top. One bug per can isn’t a problem. If you see two or three bugs per can, you have a moderate infestation. Five or more bugs suggest a severe infestation.
Taking Good Care of Your Lawn
Before you treat your lawn, there are a few things you can do to improve your chances of success and discourage the bugs from coming back. Mow the grass to the maximum height recommended for its variety, but avoid mowing more than one-third of the grass height at a time.
Chinch bugs live in the thatch, the layer of dead grass clippings that builds up on the soil. Remove thatch that’s built up to more than 1/2 inch deep using a thatch rake. If your thatch isn’t this thick, aerate the soil with a manual or automated aerator or by using spiked lawn aerating shoes.
After you’ve treated your lawn, apply compost, aged manure or other organic matter to improve the soil conditions. Use a slow-release fertilizer to further strengthen your grass. Avoid over-fertilizing, especially with a high-nitrogen fertilizer. This can leave your grass soft and more vulnerable to insect attacks.
Mow often to keep grass clippings short so they’re less likely to build up. When the weathers hot, keep your lawn well watered, but don’t overwater. Water during the cooler times of the day, such as early morning or towards evening to avoid burning the grass. In fall, aerate and fertilize the lawn again.
Clearing up a Moderate Chinch Bug Infestation
For a moderate chinch bug infestation, vacuuming the lawn is the easiest solution and one of the most effective ones, too. First, rake the grass thoroughly starting 2 feet out from the edges of the affected area, working from the edges toward the center. Use a wet-vac to vacuum the entire area you raked, then water the lawn.
For another way to treat infestations in limited areas, spray down the affected areas with mildly soapy water, paying close attention to the border between the damaged grass and the healthy grass. Spread a white flannel sheet over the area and wait around 15 minutes. Pull the sheet back, and you should see the bugs attached to it. Remove them and put them in a bucket of soapy water.
To get a more wide-spread infestation under control, sprinkle a fine layer of diatomaceous earth over the lawn. This natural substance kills chinch bugs and other damaging insects, but won’t harm earthworms, plants, pets or people. Nature can help you clear up moderate infestations, too.
Scatter bird seed on areas infested with chinch bugs to attract birds that will eat the bugs along with the seed. Applying nematodes, microscopic worm-like organisms, to the lawn may also help. Proper watering encourages the growth of the fungi Beauvaria bassiana, which attacks chinch bugs.
Dealing with Major Bug Problems
If you have a moderate yet stubborn infestation where gentler treatments haven’t worked, treat the grass with insecticidal soap. Many brands made with natural ingredients are safe for use around children and pets, and are even approved for use on organic gardens.
For an infestation that’s either severe, spread over a large area or both, insecticides containing bifenthrin and acephate can help. Apply granulated insecticide with a fertilizer spreader or liquid insecticide using an insecticide attachment on the end of a garden hose.
Most of these products are more effective on a recently watered lawn. That said, always follow the manufacturers instructions because correct application methods vary from product to product. For heavy infestations, you might need to retreat the lawn every two weeks until the chinch bugs are gone.
When you’re dealing with a chinch bug infestation that just won’t go away, it’s worth consulting an exterminator. A professional can bring insecticides you might not have access to, apply them safely, and advise you on correcting the conditions that are attracting the bugs.
If you’re thinking about re-planting your lawn, avoid St. Augustine grass, which is a favorite of chinch bugs. Zoysia grass is somewhat less attractive to these insects, but Bermuda grass, buffalo grass, and bahia grass are even better choices for a chinch-bug-free lawn. Beyond this, proper lawn care goes a long way towards keeping these insects away.