If you haven't already tried....

Parasitic nematodes and/or pyrethin which'll
kill more than the webworms

Unfortunately I cant find nematodes in my area and to ship them here overnight is very expensive. I will look into the pyrethin, thanks.

As I was spraying B.T. on my lawn last night I noticed a Praying Manits on one of the grass blades. First one I've ever seen in my lawn. I then noticed a few wolf spiders crawling around in the grass.

I hope these guys are eating/helping me battle the sod webworms.

Try this link for your nematodes, they aren't very expensive.

Here is a link that might be useful: Guardian Nematodes