Reports to various Correspondents. 19 



in places where no sheep have been for twenty-four months. In the 

 latter case, I feel sure the cause is due to distribution by starlings, 

 ■t;tc. The chances of these Acari living over the winter is very small 

 when detached from the sheep ; and, from those I liave tried to keep, 

 I do not think, given sun, wind, and rain, they will live imany weeks 

 away from their host. AVetness is very harmful to them — a heavy 

 drenching with cold water kills them readily, but, of course, does not 

 affect the eggs. I have been unable to keep them alive many days on 

 damp, sodden ground, and found the eggs then hatched out and the 

 larva; perished. 



The way in which they live longest detached from the host is 

 when tags of wool and scabs get torn off by the sheep on hurdles, 

 hedges, etc. 



The eggs may remain dormant up to possibly eleven days. This 

 is the longest period recorded. I feel sure that is very exceptional, 

 probably only in very cold, dull dry weather. I once kept some ova 

 in a dry temperature of 30° F. for two months, and then being raised 

 to 67° F. a few of them incubated. Varieties of Psorrrptes occur on 

 horses, goats, rabbits and cattle, but they will not attack sheep, nor 

 •will the sheep form attack them. 



With regard to extermination, of course dipping is the main thing, 

 and for this one must have a sulphur or tobacco dip. Dipping should 

 be done twice at least to be completely effectual. The second dip 

 should be about ten days after the first. I have noticed the acari 

 become active about May, and in bad cases I should certainly say 

 dip before the sheep are shorn, but dipping is most effectual afterwards 

 (from four to six weeks). 



Spring dipping before shearing can only be partly successful, but 

 if the flock is bad it would be worth while. It has another point 

 in its favour — destruction or removal of the Ticks, " Keds," and 

 Lice (Trichodectes) ; but for scab alone, after shearing would be best 

 for compulsory measures. As a rule sheep are dipped from four to 

 ■six weeks after shearing. The fleece has then sufficiently grown to 

 be able to hold the dip. Sheep of course are often put back on the 

 same land after dipping, w^iich is foolish. All pens should be well 

 disinfected, and also the ground where shearing has taken place, 

 another point often overlooked. I once found fifty ticks and any 

 number of " Keds " in a few yards around the men shearing at home. 



With regard to a dye in the dip, one would have to proceed very 

 cautiously. If one is known tliat will not affect in any way the wool 

 and will disappear, it certainly would be an excellent plan, but if only 

 used after shearing it would not matter. 



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