10 



BULLETIN 147, U. S. DEPABTMENT OF AGEICULTURE. 



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 



