In studies on factors influencing the attractiveness of cords to house flies, sisal or cotton cords were more attractive than jute or wool cords. Attractiveness of the cords increased with cord diameter (3/64 in. to 7/16 in.) and red or black cords were the preferred colors. Cords soiled with fly fecal spots were more attractive than those treated with various chemical attrahents. In tests with insecticide-impregnated cords, those dipped in 5 or 10% parathion-xylene soln. gave essentially complete mortalities of DDT-resistant house flies with 60-min. exposures during 41-week test period. Cords treated in 5, 10, or 25% Diazinon-xylene soln. gave more than 90% mortality for 17, 26 and over 47 weeks, respectively. Cords treated with 5% parathion and 5% Diazinon showed high mortalities and rapid knockdown action during a 26-week test period. Cords treated with CS-708, DDT, NPD, nicotine, A-42, malathion, EPN, Bayer 21/199, and Bayer L 13/59 showed less promising results than cords treated with parathion and Diazinon.