Are these little piles of dirt worms, night crawlers, slugs, or ??? I live in the San Diego area. My dogs seem interested in the tiny piles of dirt. If raked away, they reappear again in the morning. Something is crawling out at night. I never see the varmit. I have St. Augustine grass.
I See Little Piles of Dirt in the a.m. In My St. Augustine Grass
Certified GKH Gardening Expert
It could be voles, moles or even snakes, all make dirt mounds that are just a few inches high. If the mounds are smaller than a few inches high, it may be ants or possibly termites. Likely, it is from moles that are looking for food, often digging and burrowing in the lawn. They are nocturnal animals, so it is likely you would not see them. Here is more information on controlling moles: https://www.gardeningknowhow.com/plant-problems/pests/mole-control-home-remedies-for-removing-moles-from-your-yard.htm
If you think ants may be behind the dirt piles, this article should help: https://www.gardeningknowhow.com/plant-problems/pests/insects/get-rid-of-ants.htm