44 LIFE HISTORY OF NORTH AMERICAN TICKS. 
Howard in Mozambique, it will probably be found to be a widespread 
insect. 
In addition to serving as intermediate hosts for various species of 
protozoa of the genera Piroplasma, Anaplasma, and Spirocheta, they 
apparently play the same réle for filarize, as has been reported by 
Grassi and Calandruccio (1890), Noe (1908), Baldasseroni (1909), 
Darling (1910), and Smith (1910). 
IMMUNE RACE OF CATTLE. 
Cattle with Brahman blood appear to be largely resistant to the 
attack of ticks. According to Borden (1910) this quality persists in 
animals with one sixty-fourth of Brahman blood. For this reason 
and the fact that they do not contract splenetic fever a large number 
have been imported into this country for breeding purposes in the 
South. 
In regard to these cattle, Mohler and Thompson (1911) state that— 
The sebum secreted by the sebaceous glands of the skin has a peculiar odor which 
seems to be repugnant to insect life. The hide, while it may be as thin as in our 
domestic animals, still appears to be much tougher and is more difficult to penetrate 
with a hypodermic needle. The hair is quite short and does not provide favorable 
shelter for the development of ticks. These three factors are probably responsible 
for the slight amount of tick molestation which these animals experience. 
In our native cattle a considerable individual variation in the 
susceptibility to tick attack is seen in the same breed of animals. 
The length of the hair and condition of the skin of the host seem to 
be the principal factors influencing tick attack. 
ARTIFICIAL CONTROL. 
Ticks may be controlled by picking or brushing them from the 
host and destroying them, by smearing or spraying the host with a 
disinfectant solution, or by dipping the host in a vat which contains 
a solution sufficiently strong to kill the ticks and not injure the host. 
For the details relating to these methods reference should be made 
to bulletins by Mohler (1905, 1906), Graybill (1909), and Hunter and 
Bishopp (1911b). 
The method by which the cattle tick may be eradicated through 
a rotation (starvation) system suited to the farm or by a combina- 
tion of rotation and dipping is also described in the bulletins of 
Mohler and Graybill above mentioned. Additional information will 
be found in bulletins by Newell and Dougherty (1906), Hunter and 
Hooker (1907), Cotton (1908), Hunter and Mitchell (1909), and 
others. Control methods are briefly considered under the several 
species. 
Restriction of the dissemination of some species may be brought 
about through quarantining the hosts, as has been done with the 
cattle tick in this country. 
