PPvACTICAL CONTROL OR ERADICATION. 33 
allowed to roam into the brushy land on the edges of the valley they 
might assume importance, but as the present plan of keeping them 
confined to areas where, for all practical purposes, ticks do not 
occur will undoubtedly be continued in the future, it is considered 
safe to ignore them in a plan of practical eradication. 
(2) Aside from the domestic animals the w T ild species which have 
been found to carry the tick must be considered. These wild mam- 
mals can be divided for the purposes of this discussion into two 
groups, namely, those small forms which frequent the floor of the 
valley and extend in some cases to considerable elevations in the 
mountains, and the larger forms, like the bear, deer, elk, and moun- 
tain goat, which are more or less confined to the mountainous walls 
of the valley, but nevertheless sometimes visit the fields below. 
Regarding the small wild mammals found throughout the valley. 
it was ascertained by examination of very large numbers of speci- 
mens that they seldom or never serve as hosts for the adult tick-. 
The immature forms of the fever tick are frequently to be found 
upon these mammals, but the development of the adults is practically 
restricted to the larger domestic animals. 
Regarding the larger wild mammals it may be said that their 
numbers are rapidly decreasing. Some of them are practically 
extinct. The mountain goat, which appears more or less frequently 
to carry the adult fever tick, never invades the valley proper. In the 
winter it is to be found upon the lower rocks of the mountain walls, 
but it moves back to higher elevations as the snow melts. There- 
fore mountain goats tend rather to remove ticks from the valley 
than to plant them there. Among the other possible hosts, the two 
species of deer are rapidly becoming scarce. Moreover, in our in- 
vestigations no fever ticks have been found attached to deer. The 
bear, among the wild mammals, is probably the most likely to serve 
as a host for the fever tick. It can not be considered that this mam- 
mal i< abundant enough, however, to have any important bearing on 
the situation. The same is true of the coyote. In fact the number of 
ticks that could possibly be reared upon all the Larger wild hosts would 
not be sufficient to cause any considerable infestation of the valley. 
These mammals can not be ignored altogether, but it i- safe to con- 
sider them as comparatively unimportant. They might be oi' con- 
siderable importance if the project were to exterminate the fever in 
the valley and surrounding regions absolutely. But the plan here 
proposed is to reduce the cases o^ spotted fever to a practically neg- 
ligible number in the valley. This i> feasible and can be accom- 
plished at small cost, while total eradication of the fever ticks in 
the mountains is not necessary t<- relieve the situation. 
Since it has been pointed out that the larger domestic animals — 
horses, at tie. sheep, and dogs — are necessary hosts for the propaga- 
