Sandboxes

What insect digs tiny sand pits in the ground?

I see these shallow little holes in the yard every summer, hardly bigger than my fingertip. I can never figure out what makes them.

Public Comments

1. My parents have mud wasps that use dirt to build their nest. I'm not sure if "mud wasp" is the actual term, but that's what my dad calls them.
2. Small Spiders, stink bugs, lizards, geckos, wasps. maybe
3. that insect is called a "Antlion"
4. maybe one of the miner bees... solitary bees that live in the ground