AntLions!

[RobertH]

In a dry area under my porch, I've noticed conical depressions with holes like this
in the last day.     They appeared overnight, and Lynwood told me they're antlions.
They are larvae of a doodlebug, and trap ants and eat 'em!
Evolution presents us with some very interesting ways to make a living.
Not dangerous to humans or pets.

   

[tulkula]

So good to finally know what those are! Thanks for sharing the wisdom

[RandyO]

Ant-lions are also known as Doodle bugs, a much more fun name.
They wait at the bottom of the cone for an ant or other bug to fall in the cone and it's dinner time ! Yum !

[burtonwc1]

Yeah but try to actually see one!