Efferia arida Williston, 1893
| Some results of desultory collecting of insects in Kansas and Colorado (1907) Kansas University Science Bulletin 4: 51-112 | |
| Robberflies of the genus Erax J S Hine (1919) Ann. Ent. Soc. Am 12: 103-154 | |
| Efferia Coquillett in America North of Mexico (Diptera: Asilidae) J Wilcox (1966) Proceedings of the California Academy of Sciences 34: 85-234 |