Size:
Adult chinch bugs are almost 3/16-inch long
Color:
Have black bodies and fully developed wings that appear frosty-white except for distinctive triangular black patch-like markings at the middles of the outer margins. Adults appear as either long-winged or short-winged forms. Newly hatched nymphs appear orange red with a pale whitish band across their abdomens. As they molt through five growth stages (instars), nymphs gradually change color from red to orange to black and develop wing pads as they develop.
Expanding, irregular patches of dead or stunted grass surrounded by a halo of yellowing, dying grass often provide the first clue to the presence of chinch bugs. These islands of dying grass tend to increase in size and merge as insect numbers increase. Damage can develop rapidly, especially in sunny locations during hot, dry weather
Chinch bugs puncture vascular tissues to extract plant juices. They secrete digestive enzymes that cause the breakdown of surrounding plant tissues as they feed. Feeding punctures can also allow pathogens to enter the plant. Consequently, damaged plants present a variety of symptoms including stunting, yellowing, wilting and necrotic lesions. Older nymphs are larger and cause more damage than younger ones. The effect of nymph feeding depends to a large degree on the health and nutrition of the plants. In particular, growth stage and water balance are critical, because small or drought stressed plants have less ability to tolerate
The common chinch bug, Blissus leucopterus leucopterus (Say) also occurs in Texas and has a wide range of host plants, including corn, rice, small grains, sorghum and bunch grasses and turf grasses. Nymphal and adult stages feed on all parts of host plants. In corn and sorghum fields, injury is most severe in early spring (March) when plants are young and drought stressed. Nymphs congregate and feed behind the sheaths of leaves. Appearance, damage and life history is very similar to that of the southern chinch bug. The false chinch bug, Nysius raphanus Howard (Heteroptera: Lygaeidae) and N. ericae (Schilling) are similar in appearance and habits to chinch bugs, but feed primarily on the seed heads of sorghum and weed seeds.
Chinch bug damage can be confused with certain lawn diseases or other physiological disorders. Brown patch is a common disease affecting the leaf blades of St. Augustine grass. Brown patch symptoms, however, usually occur in a circular or semi-circular pattern, as opposed to the irregular-shaped areas of dead and dying grass that result from chinch bug feeding. Chinch bug damage also can be difficult to distinguish from that caused by drought. Detection of significant numbers of the insects themselves is the best proof that chinch bugs are the cause of the damage.
Chinch Bug Prevention Tips
- Cultural controls:
- Control of chinch bugs starts with proper lawn care. Keeping thatch to a minimum, for example, reduces chinch bug numbers and makes other control methods more effective. Thatch is the layer of dead plant material found between the green tops of the grass plant and the soil below. Thatch provides a protective home for chinch bugs, and chemically binds with many insecticides, making such controls less effective.
- Proper mowing practices can help reduce thatch build up. For optimum turf grass health, no more than 35 to 40 percent of the leaf blade should be removed at a time when mowing. This means that lawns generally should be mowed no less often than once a week during the growing season. Mulching- or recycling-type mowers tear grass clippings into small pieces that are decomposed more easily by soil microbes.
- When thatch exceeds 1 inch in thickness, it may be necessary to have your lawn “vertically mowed.” Vertical mowing (a method of physically removing thatch) can be performed by a professional lawn maintenance company or by doing it yourself. Vertical mowing can temporarily harm your lawn’s appearance because it destroys the tightly woven stolon system of St. Augustine grass. Vertical mowers can be obtained through many equipment rental stores.
- Lawn aeration, in combination with top-dressing, also can help reduce thick layers of thatch. Aeration is performed by punching holes in the turf to increase air and water penetration. Lawn aeration machines can be obtained from many equipment rental stores, or aeration can be performed by a professional lawn care company. Aeration, in combination with top-dressing, helps correct moderate thatch problems by increasing soil-to-thatch contact, thus speeding up microbial decay.
- Over-application of fertilizer also contributes to thatch formation and makes lawns more attractive as a food source for chinch bugs. No more than 3 to 4 pounds of nitrogen (N) per 1,000 square feet should be applied each year to St. Augustine grass growing in sunny locations. Grass in shady sites needs no more than 2 pounds of nitrogen per 1,000 square feet each year. Organic, or slow-release fertilizers, reduce the risk of over-fertilization because they release nitrogen more slowly.
- Too little or too much water also can cause chinch bug problems. Chinch bugs prefer hot, dry environments. Dry weather enhances survival of chinch bug nymphs and eggs by reducing the incidence of disease. Also, drought-stressed lawns are more susceptible to chinch bug injury. On the other hand, over-watering results in saturated, oxygen-deprived soils that cannot sustain the microbes needed to decompose thatch.
- St. Augustine grass lawns should be watched closely during the summer for signs of drought stress. The lawn should be watered immediately when edges of grass blades begin to curl, grass fails to spring back quickly when walked on, or the turf takes on a dull bluish-gray color. Whenever possible, apply enough water to wet the soil profile to a depth of approximately 6 inches and let it dry out between irrigations. Frequent watering promotes shallow root systems in St. Augustine-grass, making it more susceptible to injury by chinch bugs.
- Resistant varieties:
The most commonly planted St. Augustine-grass varieties are highly susceptible to chinch bug attack; however ‘Floratam’ generally provides a high level of resistance to both chinch bugs and St. Augustine.
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