If you have had a drier than normal summer and are seeing dried patches in your lawn like the one in the picture, you may have cinch bugs. Cinch bugs are small black bugs with white wings, The bite and suck the sap out of the grass and other plants. They usually only appear where is is dry and sunny. In fact Fadedegons tells us that sometimes watering the lawn deeply and keeping it damp for 3 or 4 weeks may clear up the cinch bug problem with no other efforts.
However if the watering doesn’t clear it up then Augusta Magazine has other advise. They suggest de-thatching if your lawn has a thick thatch and watering deeply once a week when there is no rain to prevent the infestation before it starts. They also mention insecticides that you can use. So if you have cinch bugs there are ways to treat your lawn to get rid of them and by watering when it is dry you may be able to prevent them coming to your yard in the first place or from expanding into your yard from a neighbors yard.