As a cool-season grass, your tall fescue lawn will grow some in the spring, but will eventually stop growing during the summer. Compared to other cool-season lawns, tall fescue is fairly drought tolerant, thanks to its deep root system. However, it can still fall prey to other summer stresses that will eradication efforts followed by over-seeding with fescue grass seed. One of these potential stresses is the hairy chinch bug.
Hairy chinch bugs (Blissus leucopterus) are small pests that can often be confused with the big-eyed bug. Adult chinch bugs will spend the winter in protected thatch layers. As soon as the temperatures indicate the arrival of spring, adult chinch bugs will begin to lay eggs. Both the nymphs and adults suck plant fluids out of the crowns and stems of the grass, and inject a toxin that interferes with the uptake of any water or nutrients. The affected grass eventually yellows and dies. The nymphs will reach adulthood and begin laying eggs again in July and August, and depending on how long the summer lasts, the second generation might be able to lay eggs as well. The damage is not so evident during the spring, while the tall fescue grass is actively growing. However, during the hot, dry conditions of summer, chinch bug damage can look a lot like drought damage. There will be yellow, uneven patches of grass that won’t recover.
How can you tell whether the damage you see is caused by drought or by chinch bugs? Take several gallon cans and remove both ends. Stick each can several inches into the lawn, and fill each can ¾ of the way with water. Wait for 10 minutes and count the number of chinch bugs, both nymphs and adults, that float to the surface (study insect guides closely and don’t mistake the chinch bugs for their beneficial predator, the big-eyed bug). If the water seeps into the soil too quickly, refill the cans. Your lawn can sustain a certain number of chinch bugs without significant damage done to it. However, if you are seeing more than 20 to 30 chinch bugs (adults + nymphs) per square foot, then you need to develop an integrated pest management plan to control them.
Integrated pest management simply means that you implement cultural, biological, and chemical means of controlling the pest, saving chemical control as a last resort. For cultural control, you must maintain the grass in a way that puts chinch bugs at a disadvantage. Chinch bugs thrive in hot and dry conditions, so one way to culturally control them is to irrigate the lawn more frequently. You could also remove your lawn’s thatch layer in the spring or fall, so that the adult chinch bugs do not have a place to hibernate during the winter. For biological control, you could introduce more big-eyed bugs to the lawn to feed on the chinch bugs. You could also try planting tall fescue seeds with endophyte, a beneficial fungus that has been proven resistant to chinch bug attacks.
If none of these methods work, or if your chinch bug problem is so severe that drastic action is necessary, you may apply a pesticide to the soil. Pick a pesticide that is safe to use on your lawn. And remember to follow all pesticide’s application instructions. Wear protective clothing, and keep out of reach of children. Pesticides are poisonous, and they will kill good bugs and bad bugs, so they should be used sparingly, if at all.
By using integrated pest management, you will hopefully limit the amount of chinch bug damage done to your tall fescue grass lawn this summer.
