207 



thorough crutching, the swabbing or dipping of infested hind-quarters in copper 

 sulphate solution, and "shower dipping" of sheep with two months' wool in an 

 arsenical dip. A series of experiments was carried out at Gindie, in Central 

 Queensland, in 1914, when it was found that no dip or dressing was effective 

 unless it was poisonous, and even then it afforded protection from fly attack for 

 only a short time. The effect of applying a strong jet of arsenical fluid under 

 considerable pressure was also tried and experiments along this line were sub- 

 sequently continued by Messrs. Brown and Russell at Dalmally, near Roma, the 

 work being carried out for the Institute of Science and Industry. Besides 

 "jetting," the result of using "shower dip" (i.e., applying the dip fluid in such 

 a way that it falls like rain on the imprisoned sheep), and ordinary dips (where 

 the sheep are forced to swim through and are actually fully immersed in a 

 narrow trough or bath containing the arsenical fluid), was carefully noted (see 

 Brown, 1919; R. S. C, 1922). Details of the method have been published 

 (R. S. C, 1922). Most of the available proprietary specifics were tried out, 

 using varying strengths, and it was found that ordinary arsenite of soda solution 

 was not only very much cheaper but more easily applied and gave better pro- 

 tection against fly attacks, as well as being harmless to the sheep and the quality 

 of the wool. 



In "jetting," a steady pressure of from 60 to 200 lbs. per square inch, 

 according to the amount and density of the wool (4 to 6 months' wool, 100 to 

 125 lbs. pressure; full fleece, 200 lbs. pressure) was made use of, about 1^ pints 

 of the fluid being the average required for the treatment of each sheep as they 

 passed singly through a narrow race when the jet was directed against the breech. 

 Up to 3,000 sheep per day could be so treated by four men, and the cost per 

 animal treated was found to be one-fifth penny. In ordinary weather 07 per 

 cent, solution gave three or more months' protection besides destroying any 

 maggots already present, but in wet weather the arsenic may be removed more 

 quickly, and hence the process may need to be repeated more frequently. It 

 was found that jetting with a solution containing 15 per cent, arsenic did not 

 aft'ect a small experimental flock, while thousands were treated with 1 per cent, 

 solution without a single instance of any baneful result. If sheep were treated 

 by jetting with a 07 per cent, solution three times a year the cost would be only 

 three-fifths penny per sheep. In the case of pregnant ewes, it was recommended 

 that if flies be not attacking, jetting should be carried out as near lambing time 

 as possible, but for other sheep the solution should be applied when flies begin 

 to attack. Even in the case of animals with skin injuries resulting from maggot 

 infestation, no losses were caused through the jetting process. 



The "shower" dip fluid contained about 023 per cent, arsenic, and animals 

 were subject to it for from 7 to 10 minutes (=:8-inch rainfall), when the fleece 

 became thoroughly wetted. In the "swim dips" it was found that 02 per cent, 

 arsenical solution destroyed lice and other ectoparasites, but was of little use as 

 a protection against fly. Strengths up to 0'5 per cent, were used without ill 

 effects being noticed either on the sheep or the wool. For ewes in lamb, weak 

 sheep, and those with 6 or more months' wool, shower dipping rather than 

 "swim dipping" was recommended, but for dry sheep and those with little growth 

 of wool, the swim dip was preferred, as it required less time to obtain the result. 



"As over 90 per cent, of the fly attack is on the breech, jetting is, as a rule, 

 the best method of protection, as it is cheaper and a stronger solution can be 

 used over the whole body. In the comparatively few cases, however, where 

 other parts of the body are attacked, jetting is obviously useless, and resort 



