The eyes of male face flies almost meet in the center of the head but the eyes of the male house fly are well separated. With a little practice, it becomes unnecessary to capture the fly to make such distinctions. Eggs are laid and larvae develop in fresh cow manure in pastures. The fly often overwinters in houses and when numerous become a household pest on warm winter and spring days. The horn fly remains on cattle day and night, leaving only to lay eggs in freshly dropped cow manure.
Horn flies feed primarily on the withers, around the horns, and along the back.
They generally feed facing downwards. During hot weather or rains, the flies may move to the belly and on cool nights may cluster around the udder. The adults live about 3 weeks and feed exclusively on cattle blood. The annoyance caused by horn flies causes milk production and weight gains to be reduced. The eggs hatch in about 20 hours and maggots develop for about 5 days before pupating.