Answer: I don't think the problem is insects and I don't think you need to fertilize. The lawn may be showing signs of stress from hot summer sunshine, or the area could indicate a fungal growth. It's sounds like Fairy ring. The symptoms are circular patches of dark green grass surrounding areas of dead or light-colored grass; mushrooms may or may not be present at the perimeter of the green area. The rings result from a fungal disease common in lawns growing in soil high in organic matter. Fungicide is generally not necessary, but if the problem doesn't subside on its own, you can treat it with a fungicide.
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