The Cicada Killer wasp is probably the most common of the digger wasps that reside in Maryland.  They are about
1 & 3/4 inches long.  They are not very agressive and very rarely sting humans. Their prey is the cicada and they can be found every year paralizing the DogDay Cicada.  They are more common every 17 years when the Periodic Cicada hatches.
Ground Digger Wasps
Maryland is blessed with various wasps and bees that dig holes and nest in the ground.  The wasps on this page dig  holes to make their nests and like many other insects, after digging the holes and laying their egg(s) the female will leave the nest, sting and paralize a different kind of insect, and place it next to their egg so their larvae that hatches from the egg will have a ready meal.
The Cicada Killer wasp is probably the most common of the digger wasps that reside in Maryland.  They are about
1 & 3/4 inches long.  They are not very agressive and very rarely sting humans. Their prey is the cicada and they can be found every year paralizing the DogDay Cicada.  They are more common every 17 years when the Periodic Cicada hatches.
Another ground digger wasp found in Maryland is the Scolia Dubia. It usually preys on the grubs of June beetles to feed it's young. They generally appear on an August morning hovering over the lawn and foliage on the sunny side of the house. They  very rarely, if ever sting humans and one can walk through them with no danger. They should not be handled.  They do very little harm and their control is generally unjustified. It may be advisable to have the lawn treated to kill the June beetle grubs and when their prey is depleted, the Scolia Dubia wasps will leave on their own.
The main reason Cicada Killers are recognized as pests is the damage they do to lawns by digging their nest holes. The holes can be up to 1&1/2 inches in diameter with a large pile of soil at the entrance. Several holes in a well manicured lawn can make it unsightly and therefore Cicada Killer control is justified. Control usually includes injecting insecticide into each individual nest hole.