An electric walk-through fly trap was evaluated for the management of the horn fly, Hematobia irritans (L.), on dairy cattle in North Carolina over 2 yr. The trap relies on black lights and electrocution grids to attract and kill flies that are brushed from the cattle passing through. During the first season, horn fly densities were reduced from >1,400 to <200 flies per animal. Horn fly density averaged 269.2 ± 25.8 on cattle using the walk-through fly trap twice daily, and 400.2 ± 43.5 on the control group during the first year. The second year, seasonal mean horn fly density was 177.3 ± 10.8 on cattle using the walk-through fly trap compared with 321.1 ± 15.8 on the control group. No insecticides were used to control horn flies during this 2-yr study.