The dog days of summer can be brutal on your lawn, especially if you have an insect attacking the grass. Insect damage can occur on both the blades and the roots and can cause yellow to brown patches and thinning turf. Before applying an insecticide, it is best to confirm the presence of a turfgrass pest. Soil compaction, improper mowing, and overwatering can also lead to thin, patchy turfgrass. There are three main ways to scout for turfgrass insects: soap flush, floatation, and soil examination. It is best to inspect multiple spots in the lawn and correctly identify the pest.
Scout for several caterpillars, two-lined spittlebugs, and mole crickets by utilizing a soap flush. Two tablespoons of dish detergent are added to a gallon of water and poured into an area of thinning or discolored turf. Lemon or orange-scented dish soap works best, and after 3-5 minutes, insects will surface. They will be dead and not attack you. Caterpillar damage tends to leave the grass looking scalped. Spittlebugs can turn the blades of grass brown and even reddish. Mole crickets can make the grass look thin and develop bare spots. For more information, please see HGIC 2488 Two-Lined Spittlebug, HGIC 2155 Mole Cricket Management in Turfgrass
If you have a St. Augustine lawn, chinch bugs could be causing your lawn to turn brown. Chinch bugs show up during hot, dry weather, and their damage is first noticed in areas that receive full sun and are close to hardscaping. Confirm chinch bugs are attacking your lawn by utilizing the water flotation technique. A cylinder open on both ends, like a coffee container with the bottom removed, is placed in an area on the edge of the discolored turf. The cylinder is filled with water and if, the insects are present will float and try to cling to the top of the side. For more information, please see HGIC 2487, Chinch Bugs
There are many species of grubs that can feed on grassroots. The grass will wilt sooner than the rest of the lawn and turn yellow. To search for grubs, you will need to exam the root zone. This is done by cutting three sides of a 1 square foot area. Pry the sod back with a shovel to look for the presence of shrubs. For more information, see HGIC 2156, White Grub Management in Turfgrass
Some insect pests like ground pearls and bermudagrass scale are difficult for homeowners to identify.
If you cannot find any turf-damaging insects, you can submit a turf sample to the Plant and Pest Diagnostic Lab.