The term “tarantula hawk” applies to more than one species of
large wasp. It even applies to more than one genus. Here in the
United States, the genera Pepsis and Hemipepsis are the only
tarantula hawks, and the largest of our spider wasps in the
family Pompilidae. Hemipepsis ustulata is a common species
across much of the western U.S., one I have encountered in both
Arizona and Colorado. It is not easy to separate Hemipepsis from
Pepsis, but I find that Hemipepsis are matte black in color, not
the iridescent blue-black that their relatives are. Hemipepsis
also tends to fly earlier in the season than Pepsis, especially
in the southwest, but both genera can be found together in the
fall, Hemipepsis being in the second generation in autumn. Wing
venation is apparently the only sure way to tell the two apart,
but most folks understandably don’t want to get that close to
such a large, stinging insect to find out which is which.
Tarantula hawks in general have interesting behaviors,
especially the males. Dr. John