It sounds like sod webworm. They are easy to kill. Here’s a link to a granular product you can use: https://www.bonide.com/products/lawn-fertilizer-and-seed/lawn-care-control/view/60613/ant-flea-and-tick-killer
And here’s a spray you can use that attaches to the end of your hose: https://www.bonide.com/products/insect-control/view/426/eight-yard-and-garden-rts