Cicada wasps are the largest wasps in North America - females reach two inches long. They're solitary, ground burrowing wasps that hunt cicadas, drag them to their nests and lay their eggs on them for the larvae to feed upon. Late July and early August seem to be the most active times for these wasps at the Indiana Dunes National Lakeshore, where I observed dozens on a single dune path. Because of their size, they can startle you, but left alone they ignore people. The males are territorial and may swoop down around you, but they don't have stingers. This is obviously a female - look at the size of the stinger.