The priesthood of the Arval Brothers called on Mars to drive off "rust" (lues), with its double meaning of wheat fungus and the red oxides that affect metal, a threat to both iron farm implements and weaponry. In the surviving text of their hymn, the Arval Brothers invoked Mars as ferus, "savage" or "feral" like a wild animal.Schilling, "Mars," in Roman and European Mythologies, p. 135; Palmer, Archaic Community, pp. 113–114.
