The southern chinch bug, Blissus Insularis Barber, is one of the most problematic insect pests of St. Augustine grass in Texas. It can be a problem anywhere St. Augustine grass is grown, causing the most damage in the Gulf Coast region and in the southern half of the state.
Chinch bug infestation typically occurs during the hot, dry months. Signs of chinch bug infestation include irregular patches of dead grass surrounded by a circle of yellowing grass. These patches are frequently observed in areas of the lawn that receive full sun. Chinch bug infestation may be confused with a brown patch or lack of moisture. Chinch bugs have sucking mouthparts that they use to suck the sap from turfgrass.
Chinch bugs are 1/6 to 1/5 inch long with black bodies. They have white wings with black triangles. Nymphs are wingless and are yellow or pinkish in color with light-colored bands around their backs.
To determine whether the lawn problem is chinch bugs, either pull back a layer of thatch or run your foot over the affected yellow area where it meets the healthy grass and watch for bugs to appear on your shoe.