Materials exhibiting a perfect repellent action for periods of from two to five days.. 30 Relation between repellent action of compounds and their composition and volatility. 30 Summary 31 BULLETIN 1472, TJ. S. DEPAETMENT OF AGEICULTUKE Certain other species of flies, such as the black blowfly, Phormia regina Meig., the green bottle flies Lucilia sericata Meig. and L. cuprina Meig., and some species of sarcophagids, particularly S. robusta Aid., not infrequently infest wounds, but they are much less important than the screw-worm fly. The black blowfly is more inclined to attack old suppurating sores and is most abundant during cool weather, hence it commonly infests animals after dehorning. It also attacks sheep in the early spring, laying its eggs on soiled wool. In this situation it is commonly spoken of as the "wool maggot." For the control of these blowflies several methods are commonly used. These are (1) the destruction of carcasses in which the flies breed; (2) the prevention of wounds, such as wire cuts, scratches, and bruises, by careful handling at the times when the animals are rounded up, dipped, etc.; (3) the carrying out of the castrating, branding, dehorning, and shearing of animals at times when flies are scarce or absent; (4) the trapping of adult flies in traps baited with meat, or, preferably, dried-egg bait; (5) the use of larvicides and repellents on infested wounds on animals. WORK OF OTHER INVESTIGATORS WITH FLY REPELLENTS Although the chemotropic responses of many insects have been studied, only a few investigators have experimented with blowflies, and no reference to previous work with repellents for the screwworm fly has been found.Cooper and Walling 2 tested the effect of various chemicals upon blowflies (Calliphora) by dusting pieces of meat with a number of different materials incorporated in precipitated chalk. The authors concluded that the following were most suitable as repellents : Methyl salicylate, para-nitramline, picric acid, creosote, green oil, boracic acid, fusel oil, pine oil, alizarine oil, origanum oil, mustard oil, sod oil, iodoform, dimethyl aniline, quinoline, allyl alcohol, aloin, saponin, copper carbonate, nitrobenzene, sinapis oil, and anise-seed oil.Olive C. Lodge 3 reported on some studies of attractive substances which might be used as baits for blowflies and house flies. She found liver to be more attractive than a number of other animal tissues and brought out the fact that the infestations of baits with larvae caused the baits to become more attractive to the flies. She mentions among the substances showing decided repellent qualities for one species of blowfly (Protophormia terrae-novae R. D.), pipendine [piperidine?], oenanthol, xylol, amyl . acetate, methyl salicylate, anisole, citral (strong), ethyl sulphocyanide, oil of thyme, of cassia, of Java citronella, of palma rosa, of bay, of heliotrope, of lavender, of cinnamon leaf, of cinnamon bark, of sassafras, of cloves, of camphor. Many other substances tested by her are classed as less repellent or neutra...