I have been noticing a lot of dead spots in my lawn and my first thought was not enough water but that is impossible as I water that zone for 1 hour twice a day. My next guess was that something like a dog, cat or deer was urinating in the area. Note: click on the picture to see a close up.
We have an old wise man in our town, he's called "Old Man Cesing" and his advice was to spray one of the brown spots with a mixture of one gallon water and two tablespoons of dish soap, wait a few minutes and then pull the grass apart to expose the insects causing the problem.
Wow! It worked like a charm and sure enough, it was sod webworm. It's the larvae that come out at night and feed on the grass (they chew it right above the thatch line). You'll find small green pellets which are called frass which is the excrement of the larvae.
I went down to my local feed and supply store and picked up a bag of bug killer that not only covers webworms, but a number of other pests as well. Below are some more pictures of what I found after the soap water test.
No matter what kind of problem you are having with your lawn, be it sections that look dead, rings, brown spots and more, simply apply the soap and water mixture and in a few minutes you'll see ton of insects pop up to the surface; simply place them in a jar, seal it and bring it to your local feed & supply store - they should be able to tell you exactly what you need to get rid of those insects.