Looks like Spittlebugs and worm casings to me too. I use Bifenthrin for spittle bug control and works for grubs too. Spittle bugs are a b_tch though. You need to do a granular treatment and spray, and then likely spray again in two weeks and maybe again two weeks later. Spray early or late while they are hopefully settled in [and feeding on your grass ;-)]. Ortho Max is retail/box store Bifenthrin.