Spray the affected turf with Bt (Bacillus thuringiensis) in a sprayer mixed in water with some Garrett Juice and maybe a little dish soap as surfactant. And be careful not to spray it all over the place, you only want to kill the worms/moths, not butterflies that might still be around this time of year.
I don't often measure closely, but in general I would mix a couple of ounces of Garrett juice and molasses at 1-2 oz. per gallon of spray. Follow the directions on the Bt bottle (usually just a teaspoon or two is needed). Here is the
Sod Webworm library entry. There is also Dipel (Bt) powder, but I haven't used it.