When varying numbers of pairs of an Afro-Asian dung beetle,Onthophagus gazella(F.), were exposed to varying quantities of bovine manure containing eggs or larvae ofHaematobia irritans(L.) in the laboratory, control of emerging fly adults ranged from 0 to 98.4 percent. Slightly greater control was achieved when the beetles were placed on manure that contained eggs than when they were placed on manure that initially contained larvae. Adult horn flies that survived the activity of beetles were smaller than control flies.