OTHER SPECIES OF TICKS. 81 
; OTHER SPECIES OF TICKS FOUND IN REGIONS WHERE ROCKY 
MOUNTAIN SPOTTED FEVER OCCURS. 
Five species of ticks other than Dermacentor venustus have been 
found to occur more or less commonly in the Bitter Root Valley of 
Montana. These are: Dermacentor albipictus Pack. (P1. IIT, figs. 
5, 6), Ixodes angustus Neum., Jvodes texanus Banks, Ixodes kingi 
Bishopp, and Haemaphysalis leporis-palustris Pack. On account of 
the host relations of these ticks it is impossible for them to play any 
important part in the dissemination of Rocky Mountain spotted 
fever. Dermacentor albipictus has been found to occur on practically 
no other animals than horses, cattle, and mountain goats. It never 
attacks man. Neither one of the three species of Ixodes has been 
found to occur on man, and they very seldom attack the domestic 
animals, being confined to certain of the small wild mammals. The 
last-named species confines its attack exclusively to rabbits with the 
exception of the immature stages, which are occasionally found upon 
birds. 
In parts of Idaho, Oregon, Nevada, and Utah, the rabbit Derma- 
centor (Dermacentor parumapertus marginatus Banks) is found 
quite commonly. Like the other common rabbit tick this species con- 
fines its attack exclusively to that host. 
SPECIES OF TICKS WHICH MIGHT PLAY AN IMPORTANT PART IN 
THE DISSEMINATION OF THE DISEASE SHOULD IT BE INTRO- 
DUCED INTO NEW REGIONS. 
Since it has been shown by Dr. Maver, of the University of 
Chicago, that Rocky Mountain spotted fever may be transmitted by 
several different species of ticks, the importance of limiting the 
disease-infested area to the territory now covered is strongly em- 
phasized. 
A closely related species, namely, Dermacentor occidentalis Neum., 
has been found to occur throughout western California and south- 
western Oregon. At present the range of this species does not over- 
Jap that of the Rocky Mountain spotted-fever tick. On account of 
the fact that this species is an important pest of man, should the 
disease become introduced into the territory where it occurs its dis- 
semination would be certain. In the eastern and southern United 
States several species occur which commonly attack man. Nearly 
all of these have host relations very similar to that of the Rocky 
Mountain spotted-fever tick, and therefore the disease might readily 
be transmitted from animal to animal and from animal to man 
by any of these species. The following species would probably be 
ef principal importance in the Southern and Eastern States: The 
fone-star tick (Amblyomma americanum L.); the American dog 
. tick (Dermacentor variabilis Say), and the gulf-coast tick (Am- 
blyomma maculatum Koch). In the extreme southern portions of 
