SHEEP TICK AND ITS ERADICATION BY DIPPING. 



11 



lowisli white to dark brown, and the shell is glossy and firm. (See 

 fig. 8.) 



Any condition which causes the sheep to bite and scratch them- 

 selves may be mistaken temporarily for ticks. In every instance close 

 examination should be made and the cause definite! v lefii-ned. It 



Fig. 7. — Lamb grossly infested with sheep ticks, showing roughened condition of fleece. 



should be remembered, however, that the presence of ticks does not 

 exclude other possible causes of the irritation, such as scab, lice, com- 

 mon ticks, bearded seeds, thorns, etc. 



ERADICATING THE TICKS BY DIPPING. 



Dipping consists of immersing the animals in a medicated liquid 

 that will kill the parasites, and is the only practicable method known 

 for eradicating sheep ticks. The process of dipping is shown in the 

 illustration on the title page. In order that the medicated liquid or 

 dip may exert its killing powers it is necessary that it come in direct 

 contact with the tissues of the parasite. There are three methods by 

 which the dip may enter the organism of the tick; first, ingestion, 

 by way of the mouth parts, through the digestive organs; second, 

 respiration, by way of the stigmata or breathing pores, through the 

 respiratory organs; third, absorption, through the skin by a process 

 of osmosis. The nonvolatile dips, such as the arsenic group, are prob- 



