This study uses morphological and natural history data, along with molecular data derived from the internal transcribed spacers 1 and 2 (ITS1 and ITS2), to investigate the status of species that are morphologically similar to Dasymutilla quadriguttata. Genetic distances, UPGMA cluster analyses, and maximum parsimony analyses were performed. In addition to those species that are morphologically similar to Dasymutilla quadriguttata, for our analysis we chose other species from the D. quadriguttata species-group that differ sufficiently in morphology as outgroups, as well as species from the D. bioculata and D. nigripes species-groups. These species include D. californica, D. chattahoochei, D. lepeletierii, D. nigripes, and D. wileyae. Conclusions from the analyses are that D. alesia, D. allardi, D. atrifimbriata, D. biguttata, D. castor, D. cypris, D. electra, D. hersilia, D. hora, D. interrupta, D. mediatoria, D. miamensis, D. mutata, D. nigridia, D. nitidula, D. permista, and D. rubricosa are indistinguishable from and junior synonyms of D. quadriguttata. With this knowledge and with past sex associations, the D. castor, D. monticola, and D. quadriguttata species-groups are updated and an addendum to Mickel's (1936) Dasymutilla key is provided.