Today I was hiking in Annadel State Park in Santa Rosa, CA. At the base of a dead Doug Fir on a shady, north-facing slope, I smelled something rancid and saw 3 mounds/piles of these muddy grubs/maggots. They were not feeding on vegetation or anything dead in the soil, or scat. It was just them in the moist dirt. I could not see any place they might have come from on the tree. There were hundreds of them - moving slowly because it was cold. Anyone know what these might be, and why they would be in such a large concentration?