Pic of lawn and of an insect. I found a number of these along the margin where color changes. Found in other areas as well but not as many. Don't know if this is the cause of the discolorization. This worm like insect is white/clear and active in the crown & thatch area of the lawn. Jumps around like a earthworm. I would say it's about 1/4" long and as wide as mechanical pencil lead.