10 
BULLETIN 147, U. S. DEPARTMENT OF AGRICULTURE. 
tick-infested group in the stable by the mangers only, and later 
turned out into a small field on account of the muddy condition of 
the barn lot, there was insufficient manifestation of small ticks to show 
pen and yard infestation. However, it was thought necessary to spray 
these cattle on occasions because of a few scattered ticks which were 
presumably carried to them on the rag with which the udders were 
washed. Spraying was followed for a day or two by a diminished 
quantity of milk, after which the normal flow reestablished itself. 
The spray used was arsenical tick dip B, a concentrated solution which 
when used in prescribed dilution produced a subsequent slight exfolia- 
tion of the epidermis. 
The deleterious effects of the ticks were not so apparent in the ex- 
periment as they would have been had more ticks been developed 
Fig, 4.— Cow No. 17, showing moderate infestation with ticks. 
early in the experiment. In that case early losses would have been 
reflected throughout. It is probable that excessive invasions of 
ticks on freshening cows in spring reduces their milk flow by fully 
one-half before the lactation period is ended. 
An attempt was made to put on about the same number of seed 
ticks at each application, so that the number applied from day to day 
was probably fairly uniform. Seed ticks secured from adult ticks 
from outside sources seemed to be less vigorous and to have more 
difficulty in attaching themselves to the cows than those more recently 
obtained from ticks that had matured on the Anthony cattle, so that 
fewer of them matured and consequently less damage resulted than 
when the Anthony ticks were used. This apparently low vitality of 
the seed ticks obtained from outside sources, together with the light 
infestation obtained at the early part of the work, delayed any 
