Horse flies and Elaeophora schneideri in the Gila National Forest, New Mexico

During June and July in 1970 and 1971, 3697 Tabanids belonging to seven species were dissected and examined for larvae of Elaeophora schneideri [cf. RAE/B 61, 2188], a filarial parasite causing blindness in North American elk (Cervus canadensis) and moose (Alces alces), in the Gila National Forest, New Mexico. Nearly 90% of the infected flies were Hybomitra laticornis (Hine). Almost 13 300 filarial larvae were recovered, with an average of 25 larvae/infected fly. Infective larvae were found in four species of Tabanids. Based on its occurrence in collections, the prevalence of infection and larval recovery, H. laticornis is considered to be the most important Tabanid vector of this filarial parasite in south-western New Mexico. H. tetrica rubrilata (Philip) and Tabanus eurycerus Philip may be important vectors in other areas.