The depth of a hole is the key to what is doing the digging. Deep holes that go out of sight indicate the hole is a residence. Shallow holes, where you can see the bottom, indicate an animal is digging for food.
Probably the holes I hear about most often are those from squirrels. Squirrels take nuts and acorns and bury them in the ground, then go back later and dig them up. But just like us, they often forget where they put them. So squirrels dig extra holes trying to find where they hid their nuts. The holes that squirrels dig are about the size of a golf ball and 1 to 2 inches deep.
Another animal that does a lot of digging and has become more prominent in the area over the last few years is armadillos.
Armadillos eat mostly insects in the ground – earthworms, grubs, spiders, etc. They are active from sunset to early morning hours and will root in lawns, vegetable gardens and flower beds looking for food. Holes are typically 1 to 3 inches deep and 3 to 5 inches wide, but the disturbed area can be as wide as 3 feet. Armadillos can tear up a yard pretty bad overnight. Their burrow is up to 15 feet long and has an entrance that is 7 to 8 inches in diameter.
Rats also dig holes but they are only going to be found in unmowed or unkept areas as they want to be inconspicuous. Occasionally they may be near shrubbery beds or wood piles. Rat holes will normally be about the size of a tennis ball, about 3 inches in diameter.
Moles tunnel, pushing up the ground as they search for insects to eat. If they encounter roots, rocks, or hard soil, they push the excess soil out of the tunnel and to the surface leaving a slight opening or hole.
Voles are small rodents that many people confuse with moles. The can construct surface runways, but most are underground. They eat a variety of plant material, mainly roots. Tunnel entrances are about the size of a 50 cent piece, about 1 to 1½ inches in diameter. Many times they are in mulched areas as voles also like to be inconspicuous.
If your yard has a healthy population of earthworms, you may find 1-inch high piles of small granular pellets of soil. These castings were passed through the body of earthworms the night before and were brought to the surface as tunnels were cleared. They are going to be more common during periods of wet weather. Many people confuse earthworm pellets with mole cricket tunnels. If ever in doubt, pour a soapy water solution over the area and see what comes to the surface.
I get a lot of calls about cicada killers. These are the large wasps that scare everybody because they are so big, about 1½ to 2 inches long. We normally see them in July and August. Cicada killers sting the cicadas and drag the immobilized insects to their nest and feed them to their developing young. Females create ½ to 1 inch diameter tunnels. They prefer areas that are dry and bare but may also be found where grass is maintained very short. You may notice a small, u-shaped mound of dirt at the entrance as well as lines in the soil where cicadas have been dragged.
There are also various solitary insects that live in the ground. Many bees will dig cylindrical tunnels in loose soil to create chambers for egg-laying. These holes may be between ¼ and ½ inch wide, about the size of a pencil. The entrance may be surrounded by a mound of loose soil as high as 2 inches. Bumblebees are solitary insects that make holes. Of course social insects such as yellow jackets build their nests in the ground too.
Birds will make holes, especially Robins and Blue Jays. Robins dig the earth looking for grubs or earthworms. You may have seen them pull up a few worms. They have an uncanny ability to detect subterranean prey. Their holes will be small as if something was poked into the ground.
Actually some of the holes we see the most are not dug by anything. Many times the roots of a long forgotten tree cut down years ago will rot away, leaving one or several mysterious holes. I have seen all sizes – from a couple of inches to 6-8 inches wide – and they go down so deep you can’t see the bottom. People will swear that something dug them.
Dogs may enlarge them with their digging. And even some creature may occupy these holes. A snake is a good example. Snakes only occupy holes, they don’t dig them. How could they? They don’t have any legs or feet for digging. If you have holes like these, just fill them in with dirt.
REACH SID MULLIS, THE DIRECTOR OF THE UNIVERSITY OF GEORGIA EXTENSION SERVICE OFFICE FOR RICHMOND COUNTY, AT (706) 821-2349 OR SMULLIS@UGA.EDU.