One hundred forty-three species of Pompilidae are recorded from Colorado, slightly more than half the number occurring north of Mexico. Some of these occur principally at higher altitudes or in the northern part of the state; this group includes 5 species of Holarctic distribution. Others (such as the tarantula hawks, Pepsis) are prevalent across the southern third of the state and range south into New Mexico and often into Mexico. Still others are widely distributed wherever there is friable soil and suitable for nesting. Certain genera are more or less restricted to preying upon certain spider taxa, while others are generalists and a few are cleptoparasites of other Pompilidae.
Evans, Howard E.
"Spider wasps of Colorado (Hymenoptera, Pompilidae): an annotated checklist,"
Great Basin Naturalist: Vol. 57
, Article 1.
Available at: http://scholarsarchive.byu.edu/gbn/vol57/iss3/1