Chinch bugs are about 3/16 inch long with black bodies and fully developed set of wings and are a major nuisance to St. Augustine grass. Even though the chinch bug has the ability to fly, it generally walks from a heavily attacked area to a fresh lawn. Research has shown that they can cover over 400 feet in an hour. The nymphs and adults use their sucking mouthparts to suck the sap from the grass until it changes from a healthy green color to yellowish-brown and dies. Homeowners know they have a chinch bug infestation when they notice expanding brown areas in their lawns.