F. C. Bisiiopp and H. P. Wood 
179 
The moose and elk, as is well known, are often heavily infested with 
this tick. Mr D. C. Nowlin forwarded us specimens collected on elk 
cows and calves near Jackson, Wyoming, April 30, 1912. He states 
that the ticks are very troublesome in that locality in the spring and 
early summer, and that he is quite sure that a percentage of loss each 
season is due to this tick, as the parasites are to be found on the elk in 
sufficient numbers to sap the vitality out of any animal. Numerous 
other reports have come to our attention of elk being found in a dying 
condition, heavily infested with this tick, leading us to believe that the 
pest must be considered in the rearing and protection of this animal. 
When the ticks are not numerous they occur mostly along the belly 
and between the legs. If numerous they are to be found on nearly all 
parts of the host. In our experiments with cattle, the ticks became 
attached in numbers on the neck and along the back, particularly above 
the shoulders and near the base of the tail. 
One of our correspondents in Oregon, Mr H. H. Hach, who has made 
many interesting observations on this tick, states that he has observed- 
a great difference in the susceptibility to attack of different horses even 
when kept under identical conditions. Often one horse in a herd of 
20 or 30 was seen to be literally covered with ticks while the others 
were very lightly or entirely uninfested. Three of our bovine hosts 
used in experiments showed such a tendency to immunity. As stated 
in Table VI (Infestation No. 8), no females became engorged on a 
Jersey calf used as a host in comparison with a bull (Infestation No. 9). 
This calf, as well as two other animals, was tested several times with 
infestations of D. albipictus without a single specimen developing to 
repletion. It should be mentioned that these hosts showed marked 
resistance to the attack of other species of ticks. This resistance 
appears to be due largely to an unusually strong tendency to form scabs 
at the point of attack, thus healing the wound and throwing off the tick 
with the scab. On all hosts scabs are usually produced as a result of 
the insertion of the mouth-parts of the ticks. When the larvae first 
become attached a translucent yellowish exudate is thrown out at the 
point of attack. The subject of resistance will be discussed at greater 
length in another publication. 
