He had me take the photo in September, and I totally forgot to follow up!!! (Bad Master Gardener!) And I'll see him this weekend! (Oh no!) He was wondering if this is the results of grubs. I thought maybe voles or moles, but it looks too much like piles of poop! I have been "digging" around on the internet for pictures that look similar, and I'm wondering if it is earthworm castings. Can you tell me what you think is causing this problem in his lawn, and what he can do about it?