What's digging holes in my yard?

THE FOLLOWING TABLE LISTS VARIOUS HOLE DIMENSIONS, SOIL CONDITIONS AND HOLE LOCATIONS, FOLLOWED BY THE CREATURE RESPONSIBLE

6 - 10 inches in diameter, no mound, scattered in lawn: skunk or raccoon

6 - 10 inches in diameter, mound four inches high, near garden or barn: groundhog

2 inches in diameter, no mound, scattered in lawn: squirrel digging acorns

2 inches in diameter, small mound one inch high, under a shrub, log pile or concrete slab: chipmunk or rat

2 inches diameter, small mound, in lawn with markedly raised grass nearby: mole

1 inch diameter, no mound, next to hosta: vole

1 inch diameter, soil thinly scattered around hole, middle of the yard: cicada killer wasp

1 inch diameter, two inches high and made from balls of mud, near creek: crayfish

One-fourth inch diameter, mound two inches high & wide, several in middle of the lawn: ground bee

No hole, mound two inches high & wide, several in middle of the lawn: earthworm