6 



FARMERS BULLETIN 198. 



24 days, and in some cases longer. However, in practical opera- 

 tions under average conditions, 24 days has been assumed to be the 



longest period. 



At the time the 

 young tick emerges 

 from the shell it is 

 almost as large as a 

 full-grown tick. (See 

 figs. 3 and 4.) It de- 

 velops very rapidly 

 and reaches sexual 

 maturity in 3 or 4 

 days. The female de- 

 posits her first pupa 

 within 8 to 10 days 

 after being fertilized. 

 The life history of 

 the sheep tick, from 

 the practical stand- 

 point, may be sum- 

 marized thus: Count- 



-Pupa of sheep tick, commonly calletl the egg, taken 

 from fleece of sheep ; enlarged. 



ing from the time when it emerges from the shell, the young tick 

 deposits its first pupa or so-called egg in about 14 days. This pupa 

 hatches into a young 

 tick within 19 to 24 

 days. These two 

 stages in the life 

 history have an im- 

 portant bearing on 

 the problem of eradi- 

 cation. 



Dipping, if prop- 

 erly done, will kill all 

 the ticks, but can not 

 be depended upon to 

 destroy all the pupa3. 

 Some of the pupa^ 

 that were in the wool 

 at the time of the 

 first dipping will 

 hatch, forming a new 

 generation of ticks. 

 This new generation 

 must be destroyed by 

 to develop and deposit pupae. On the other hand, the second 



second dipping before they have had time 



