Various branch chain saturated hydrocarbons mixed with muscalure elicit more responses from male house flies,Musca domesticaL., in pseudofly tests than either muscalure or the other hydrocarbons alone. The most active combinations were 13-methylnonacosane+(Z)-9-tricosene (muscalure) at up to a ratio of 90:10; and 13-methylheptacosane+(Z)-9-tricosene at up to a ratio of 99:1; and 4,8-dimethylheptacosane, 11-methylnonacosane, andcis-9,10-epoxy-tricosane at a ratio of 40:40:20, though the individual components of this mixture were significantly less active than muscalure.