Cicada killers in the landscape can get home owners worried due to their large size and excavation they do in the landscape. The following is more information.
Now that cicadas are out, soon to follow are the wasps that hunt them. The cicada killer wasp uses cicadas to provision its nest. Cicadas are caught and stung by the wasp, then dragged back to the nest. The most noticeable feature is often the large amount of soil excavated and mounded outside the burrow. Once in the nest, the female wasp lays her eggs on the cicada. Soon the egg hatches and the larva feeds on the cicada. When mature, the wasp larva pupates and another generation of wasps emerges to carry on the life cycle. This is one of our most "showy" wasps and the sight and sound of a collection of them in a yard is impressive. I used to say that I had never heard of anyone being stung by one until a woman from Texas sent me an e-mail message to say that she had, indeed, been stung. However, it was really an accidental entanglement that created the situation. She seemed only slightly amused to know that she held such an honor. Since they control cicadas, these wasps can be regarded as beneficial. They are also downright interesting. Ornamentals and Turf Insect Note No. 63 (http://www.ces.ncsu.edu/depts/ent/notes/O&T/lawn/note63/note63.html) has additional information on the biology and control of cicada killer wasps.
Cicada killer wasp and cicada. Photo by Ronald F. Billings, Texas Forest Service, Bugwood.org
Information from the July 10, 2009 edition of the North Carolina Pest News http://ipm.ncsu.edu/current_ipm/09PestNews/09News13/pestnews.pdf