206 



The last question to be considered is the possibihty of applying to sheep 

 some medicament containing a poison with the twofold aim of (1) destroying 

 any maggots which may be present, and (2) so poisoning the wool that it will 

 either no longer attract flies, or else will poison any larvae which may hatch 

 from eggs subsequently deposited. None of these, however, can control the 

 blowfly, though they may be the means of preventing the insects from attacking 

 sheep. Even when found to be effective for a limited time, the procedure has 

 to be periodically repeated. The use of some repellent or poison is to be looked 

 on only as a method for saving the sheep. Graybill, Phelps, and Stevenson ^''^ have 

 published certain data relating to this subject, but the information is not applic- 

 able to the Australian problem. Cooper and Walling ("' carried out experiments 

 with a large nvmiber of chemical substances in order to test their value against 

 blowflies or their larvae. The following were found, under laboratory con- 

 ditions, to be repellent to the adult insect (and therefore protective), when 

 applied, diluted with precipitated chalk, to pieces of meat exposed for 17 days 

 in England : — Methyl salicylate, p-nitraniline, picric acid, creosote, green oil, 

 boracic acid, fusel oil, pine oil, alizarine oil, origanum oil, mustard oil, sod oil, 

 iodoform, dimethylamine, quinoline, allyl alcohol, aloin, saponin, copper car- 

 bonate, nitrobenzine, sinapis oil, and aniseed oil. The substances applied in 

 powder form (by using precipitated chalk as a basis) found to be most toxic 

 to blowfly larvae were arsenic sulphide, nitrobenzine, eucalyptus oil, methyl 

 salicylate, cedarwood oil, p-nitraniline, B-naphthylamine, oxalic acid, borax, 

 quinoline, allyl alcohol, picric acid, dimethylamine, copper carbonate, oil of 

 cloves, turpentine, B-naphthol, creosote, fusel oil, sinapis oil, aniseed oil, and 

 iodoform. It need hardly be pointed out that expense would prevent many of 

 these from being used. Some would probably detrimentally affect the wool, vrhile 

 others would be too readily removed by rain. 



Work was undertaken in New South Wales and Queensland for many 

 years with a view to determining what dips and dressings might be satisfactorily 

 used. J. L. Froggatt carried out a number of experiments with certain sub- 

 stances — phenols, cresols, pyridine, resin, turpentine, copper sulphate, iodoform, 

 eucalyptus oil, sulphur, pyrethum, various mineral oils, fish oils, and arsenic. 

 The effect of many proprietary dip fluids on maggots was tested, and it was 

 reported that in most cases not more than 50 per cent, of the maggots were killed 

 after one hour's immersion in them. He did not make any recommendation 

 (1916). A summary of his earlier work was given by his father in 1915 (see 

 also Froggatt and Froggatt, 1917, pp. 15-19). The following three mixtures were 

 recommended later (Froggatt and Froggatt, 1918, p. 14) as suitable for swabbing 

 infested areas: — Spirits of tar and kerosene, 1:3; arsenite of soda, 1^ lb. in 

 50 gallons of water; castor oil and turpentine, 1:5 (rather expensive); while 

 in regard to copper sulphate solution it was stated that though it deodorised 

 wool and thus prevented reinfestation, it stained the wool and aft"ected the skin. 

 In 1920 McDougall gave an account of some spraying experiments at Trangie, 

 New South Whales. The following swabbing fluid was ultimately recommended 

 by Froggatt (1922, p. 104) :— Water, 25 gallons; oil, 20 gallons; soap, 10 lbs.; 

 arsenite of soda, 1| lb. (or arsenic 1 lb. and caustic soda 3 ozs.). 



A brief survey of Queensland experience in regard to treating sheep may 

 now be given. Cory (1913, p. 8) recommended, amongst other measures, 



C-' Graybill, H. W., Repellents for protecting Animals from the Attacks of Flies, Bull. 

 131, U.S.D.'A., 1914. Phelps, E. B., and Stevenson, A. F., Experimental Studies with 

 Muscicides and other Fly-destroying Agencies, Bull. 108, Hyg. Lab. U.S. Public Health 

 Service, 1917. 



(3) Cooper, A. F., and Walling, W. A., The effect of various Chemicals on Blowfly, Ann. 

 Appl. Biol, 2, 1915, pp. 166-182. 



