INFECTIOUS DISEASES OF CATTLE. 



503 



Dipping in a vat. — Farms and pastures may be freed of ticks by 

 treating- all cattle at regular intervals with an effective tick-destroy- 

 ing agent. If the treatment is applied with such success as to destroy 

 all ticks that reach the cattle from time to time, thus preventing 

 any engorged females from dropping on the pasture after the begin- 

 ning of the treatment, the pasture will become free of ticks after 

 the same period of time has elapsed as would have been required 



Pail spraying pump for small herds. 



if all animals had been excluded, beginning on the same date; that 

 is, a perfectly successful treatment would be practically the same as 

 the complete exclusion of the herd. The dates on which the starving 

 out of an infestation will be effected when begun at various times 

 of the year have already been given in the table on page 494. In 

 actual practice, however, the best treatment will in many cases not 

 be absolutely successful, as some ticks will escape and may reinfest 

 the pasture, and thus prolong the time necessary to accomplish 



