Hairy chinch bugs can be frequent pests of home lawns in Pennsylvania. They are often associated with open, sunny areas and may be as numerous as 150 to 200 insects per square foot. 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.
An adult hairy chinch bug is about 1/6 inch long, has a gray-black body with fine hairs, white wings, and reddish legs. The outer margin of each forewing has a small, black, triangular spot. The wings of the adult are folded flat over their backs
Hairy chinch bugs prefer feeding on red fescues, perennial ryegrass, bentgrass, and Kentucky bluegrass. Chinch bug infestations frequently occur in turfgrass with thick thatch that is exposed to full sunlight during periods of hot, dry weather. 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 bug nymphs and adults cause significant feeding damage by removing plant fluids and by injecting a toxin that causes the grass to yellow, turn reddish brown, and eventually die. Chinch bug damaged areas often coalesce into large patches of dead, brown grass. The suggested economic threshold for chinch bug is 15 to 20 insects per square foot.
Visual inspection of healthy turfgrass bordering the dead turfgrass is one sampling method for chinch bugs. The fast-moving adults and nymphs can be seen scurrying about at the base of grass stems and aggregating in groups. However, these insects frequently blend in with the thatch and go unnoticed. On a sunny day, you will notice adults crawling across driveways, sidewalks, and/or over foundation block walls. Hairy chinch bugs can be detected by removing both ends of a one-gallon can, driving the can several inches into the soil, and filling it three-quarters full with water. Stir the duff at the bottom of the container to dislodge chinch bugs located in the thatch. The disturbed chinch bugs soon float to the surface. Count the number of adults and nymphs floating to the surface over a 10-minute period, but do not confuse them with the beneficial big-eyed bug. Refill the can if the water soaks into the ground before the end of the 10-minute sampling interval. Researchers suggest that 20 to 30 chinch bug life stages per square foot may warrant control, especially when chinch bugs are actively feeding during the summer months.