Chinch Bugs, Their Damage and Elimination
Chinch bugs are most damaging to St. Augustine grass. You may see them on grasses such as zoysia, Bermuda, and centipede, but infestations usually occur where high populations have built up on St. Augustine grass. Adult chinch bugs are about one-fifth of an inch long and black with white wings folded over their backs. The insect mates early in the season when the temperature reaches 70 degrees Fahrenheit. The female lays eggs on roots, stems, leaves, leaf sheaths or crevices in nodes and other protected places. Eggs are laid over a 2 to 3 week period, with one female laying as many as 500 eggs.
The young chinch bugs ( called nymphs) develop into adults in four to six weeks. Nymphs are yellow upon hatching but soon turn red and have a light colored band across their abdomens. With each molt, nymphs more closely resemble the adults. There are 2 to 4 generations per year.
The chinch bugs insert their slender beak into the grass and suck the plant juices. As the chinch bug sucks the plant juices, it releases a toxin that causes yellowish to brownish patches in turf. Typical injury appears as spreading patches of brown, dead grass. This pest is a sunshine-loving insect and seldom attacks grass in a dense shady area. Discolored areas caused by chinch bug feeding that are in open sunlight several hours daily may be "hot spots" for chinch bug damage. Most homeowners will first notice dead patches of grass along a driveway, curb, sidewalk or foundation of the home, due to the heat emitted from such objects.
Because they can fly, it is difficult to keep an area free of chinch bugs if they are emerging from neighboring lawns, golf courses or nearby croplands.
Scout turf on sunny days by slowly sliding your foot through the sod and watching for the bugs to crawl across your shoe. You can also determine infestations by using a large coffee can or gallon can with both ends removed. Press one end of the can about 2 or 3 inches into the soil, fill with soapy water, and watch for about 5 minutes. If chinch bugs are present, they will float to the surface. (This test will also bring molecrickets to the surface) It is very important to check areas where the yellowish spots and the green grass meet in several different locations.
Chinch bugs have become resistant to almost every pesticide used to control
them. They were even resistant to DDT in the early 1950s. Of the many
insecticides labeled for chinch bug elimination, there is one active ingredient that stands out above the
rest: Bifenthrin. Talstar
IT both contain Bifenthrin.
Bifenthrin should be applied through a hose end sprayer at the rate of 1/2 ounce per 1000 square feet. Talstar granules should be applied at the rate of 25 pounds per 1/4 acre and irrigated immediately after application.
Thatch removal is important for eliminating conditions favorable for chinch bug survival. Maintaining adequate moisture will increase the tolerance of turf to feeding damage and will promote beneficial fungi that attack chinch bugs. Low nitrogen fertilization slows chinch bug reproduction although the lawns regularly attacked by these insects (St. Augustine) are heavy feeders and prefer more fertilizer than other turf grasses. Consult your local county extension office about feeding your St. Augustine grass.
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