Chinch Bug
Blissus leucopterus leucopterus (Say), Lygaeidae, HEMIPTERA
Adult-The adult chinch bug is about 4 mm long and black with opaque wings. The wings may be as long as the body or 1/3 to 1/2 the length of the body. In either case, each wing bears a distinctive, triangular, black mark

Damage to lawns is noticed mostly in hot dry conditions, usually in late summer.
Cultural practices include, mowing lawn on a high setting, effective weed control and ample watering.
Chemical controls include Sevin