Chinch bug infestations frequently occur in turfgrass with thick thatch that is exposed to full sunlight during periods of hot, dry weather. Grass attacked by chinch bugs looks like grass suffering from drought. Chinch bug nymphs and adults cause significant feeding damage by inserts its straw-like mouthparts into the plant tissue and sucks out the plant fluids while injecting a toxin into the plant which clogs the vascular system and eventually causes the grass to yellow, turn reddish brown, and eventually die. Damaged areas first appear as small, irregular patches, which enlarge into large patches of dead, brown grass as the insects spread.
Chinch bugs are often associated with open, sunny areas. Typically starting along driveways and sidewalks, affected grass blades wilt, turn yellow-brown, then dry out and die. Chinch bug populations frequently go unnoticed because of their small size and coloration, which blends in with turfgrass and thatch. Chinch bug damage may be masked during periods of drought. Chinch bug damage is often less noticeable during the spring and early summer. Damage frequently appears from early July through late August when the insects are actively feeding.
Chinch bugs are very small so you have to look for them. Examine the grass in the marginal areas of injured patches, not in the clearly dead grass. Spread the grass gently with your fingers and look in the thatch, near the soil surface. Chinch bugs are usually very active in the summer, so you will be able to see them scurrying around, especially on warm summer days.
If you don't see them when you get down on your hands and knees in your lawn, try the tin-can method. Cut out both ends of a large tin can, such as a coffee can, making a tube. Soften the soil a little with water, and push one end of the can into the ground at least 5 to 2-3 inches deep, leaving at least 4 inches of the can above the ground. Then pour water into the can and keep it filled for 5-10 minutes. If you have chinch bugs, they'll start floating up to the surface where you can count them. You may also see chinch-bug nymphs, which range from pink to red and have a white stripe across their middles. If you've checked for chinch bugs and are still not sure you have them, call a professional.