The results of a 4-year test indicate that fly traps placed in a very light shade, near a large body of water or running stream, protected from direct wind and surrounded with timber and underbrush of medium density, should prove highly efficient in trapping Cochliomyia spp. and Phormia spp. Blowfly traps placed in open sunlight where they are protected from direct wind and surrounded with timber and underbrush of medium density catch the greatest number of Cochliomyia spp. Wool maggot flies, Phormia spp., prefer more shaded areas and higher humidity, with more surrounding timber and underbrush.