8 
BULLETIN 147, U. S. DEPARTMENT OF AGRICULTURE. 
cow seemed to resist the effects of the ticks until toward the end of 
the experiment, but finally failed rapidly in giving milk and died 
within a week after the close of the experiment. 
Fig. 1.— Cow No. 15, heavily infested with ticks over the entire body. This was one of the best cows in 
the group, but she died of tick fever shortly after the close of the experiment. Photo taken Sept. 25, 
1913. 
Cow 20 was infested almost as heavily as cow 15. She was a large 
Jersey-like cow of lemon-yellow color. (Fig. 2.) Her milk failed 
quite early in the experiment. She presented a dejected appearance 
Fig. 2.— Cow No. 20, heavily infested on neck and shoulders. Photo taken Sept. 24, 1913. 
for some time but later recuperated and gained or held her weight 
to the end. Externally there seemed to be no reason why ticks 
developed so much more on her than on cow 14. 
