646 MANAGEMENT OF SHEEP EXTERNAL PARASITES 



a rose can, or still better, a lime-wash spraying machine, is 

 a common practice when large numbers of sheep require to 

 be protected. The sheep are first packed closely together 

 in a fold, so that the dipping stuff when showered on cannot 

 fall to the ground. Maggots have been known to effect great 

 improvement in a bad case of foot-rot by feeding on the 

 diseased part, but their work would be difficult to regulate 

 as a remedy for the ailment 



Scab-mites are microscopic, and very much smaller 

 than any of the other parasites. When they are present, 

 patches of the wool become white, and the sheep by biting 

 detach quantities, and leave the wool in little white locks 

 which give a rough and speckled surface. When felt by hand, 

 there is a hard brittle scab on the skin at the roots of the 

 wool, under which the creatures shelter. This scab must of 

 necessity be cleared off to prevent the extension of the 

 disorder, which is most contagious, and would ultimately 

 prove fatal to life if not attended to. "The Highlands of 

 Scotland," or north of the Forth and Clyde, was at one 

 time the stronghold of scab, but the chief centre of infection, 

 as shown by the weekly returns of outbreaks of the Board 

 of Agriculture, has been transferred to Wales. It is to be 

 regretted that it still lurks in some places in this country, since 

 it is possible to stamp it out, as has been proved by the 

 energetic action of the Stock Departments of the leading 

 Australasian Colonies (States) 3 where it has been completely 

 eradicated. After a long drive or railway journey, when sheep 

 from the Highlands of Scotland or Wales are packed closely 

 and heated, scab is liable to break out in a few weeks, although 

 not observed in the flock from which they came. The rule is 

 to dip Highland sheep about a week, but not more than ten 

 days, after coming off rail, and the danger disappears. 



The Life-History of the Scab Parasite. 1 



The common scab, otherwise termed " acariasis " and 

 " itch," of sheep is due to the injurious action of the scab- 

 mite, Psoroptes communis, Fiirst, var. ovis. This parasite is 

 confined to sheep, and lives upon those parts of the skin 



1 From the Author's paper on " Scab in Sheep " in the Transactions 

 of the Highland and Agricultural Society of Scotland^ 1900, q.v. 



