Reports to variotis 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, 
etc. The chances of these Acctri living over the winter is very small 
when detached from the sheep ; and, from those I have tried to keep, 
I do not think, given sun, wind, and rain, they will live imany weeks 
away from their host. Wetness 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 
larvae 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 Psorojptes occur on 
horses, goats, rabbits end 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, which 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 that 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. 
