Epeolus occidentalis Cresson, 1878:87, ♂♀. 20 ♂♀, Colorado (leg. Ridings). - Cresson, 1879Cresson, E.T. 1879. Catalogue of North American Apidae. Transactions of the American Entomological Society and Proceedings of the Entomological Section of the Academy of Natural Sciences 7:215-232. (distribution); Fox, 1893Fox, W.J. 1893. Report on some mexican Hymenoptera, principally from lower California. Proceedings of the California Academy of Sciences ser.2 (4):1-25. (distribution); Dalla Torre, 1896Dalla Torre, C.G. 1896. Catalogus Hymenopterorum hucusque descriptorum systematicus et synonymicus, X. Apidae (Anthophila). Sumptibus Guilelmi Engelmann, 1-643. (distribution); Cockerell, 1898Cockerell, T.D.A. 1898. Appendix to article III. Volume XI. Notes on bees taken at Albuquerque, New Mexico, in September, 1897. Bulletin of the University of New Mexico 1:72-73. (distribution); Cockerell, 1899Cockerell, T.D.A. 1899. Catálogo de las Abejas de Mexico. Biblioteca Agricola de las Secretaria de Fomento, Mexico, 1-20. (distribution); Cockerell, 1899Cockerell, T.D.A. 1899. The bees of Kansas. Entomological News 10 (1):3-4. (distribution); Cockerell, 1903Cockerell, T.D.A. 1903. A catalogue of the bees of California. Psyche 10:74-78. (distribution); Brues, 1903Brues, C.T. 1903. Studies of Texan bees. Part 1. Entomological News 14:79-85. (distribution); Cockerell, 1903Cockerell, T.D.A. 1903. North-American bees, and a new Homopteron. The Annals and Magazine of Natural History ser. 7: v. 12:442-455. (distribution). - As Deringiella occidentalis: - Nava-Bolaños & Osorio-Olvera, 2022Nava-Bolaños, A. & L. Osorio-Olvera 2022. Estado del arte del conocimiento de biodiversidad de los polinizadores de México. Revista Mexicana de Biodiversidad 93:1-77. (distribution). - As Triepeolus occidentalis: - Cockerell, 1904Cockerell, T.D.A. 1904. Some parasitic bees. The Annals and Magazine of Natural History ser. 7: v. 13:33-42. (distribution); Viereck, 1905Viereck, H.L. 1905. Synopsis of bees of Oregon, Washington, British Columbia and Vancouver.—IV. The Canadian Entomologist 37:277-287. (distribution); Cockerell, 1906Cockerell, T.D.A. 1906. The bees of New Mexico. Transactions of the American Entomological Society 32:289-314. (distribution); Krombein et al., 1979Krombein, K.V., P.D. Hurd, D.R. Smith & B.D. Burks 1979. Catalog of Hymenoptera in America North of Mexico. Volume 2. Apocrita (Aculeata). Smithsonian Institution Press, Washington D.C. 1199-2209. (distribution); Rightmyer, 2008Rightmyer, M.G. 2008. A review of the cleptoparasitic bee genus Triepeolus (Hymenoptera: Apidae).-Part I. Zootaxa 1710:1-170. (distribution).