During June and July, 1970 and 1971, 3697 of 15,223 horse flies (Diptera: Tabanidae) belonging to seven species were dissected and examined for larval Elaeophora schneideri Wehr and Dikmans, 1935, in the Gila National Forest, New Mexico. Hybomitra laticornis (Hine) comprised 90 percent of the six infected species. Almost 13,300 larvae were recovered with an average of 25 larvae per infected fly. Infective larvae were found in four species. Based on occurrence in collections, prevalence of infection and larval recovery, H. laticornis is considered to be the most important horse fly vector of this filarial parasite in southwest New Mexico. H. tetrica rubrilata (Philip) and Tabanus eurycerus Philip may be important vectors in other areas.