SHEEP TICK AND ITS ERADICATION BY DIPPING. 



The egg is not laid, but is retained in the body of the female, where 

 it develops into a larva in about 7 days. At the time of birth the 

 larva is covered with 

 a soft white mem- 

 brane, which turns 

 brown and becomes a 

 hard shell, called a 

 puparium, in about 

 12 hours. (See fig. 2.) 

 The term pupa ap- 

 plies to that stage in 

 the life of the sheep 

 tick from the time 

 it is born until it 

 hatches into a young 

 tick. During this 

 stage the pupa re- 

 mains within its hard 

 shell or puparium, 

 which is attached to 

 the wool fibers by a 

 glue- like substance 

 which dissolves read- 

 ily in water. These 

 shell - covered pupa* 

 are commonly called 

 eggs. In from 19 to 

 2-t days from the time 

 it is deposited the 

 shell of the pupa is 

 broken open at one 

 end and the young 

 tick emerges and be- 

 comes active in the 

 fleece. The time be- 

 tween the depositing 

 of the pupa and the 

 emergence of the 

 young tick is usually 

 called the period of 

 incubation, and its 

 duration is influenced 

 by the temperature, 

 incubation is about 19 davs, while during cold Aveather it is about 



Pig. 1. — Comparison of form and structure of sheep tick 

 and true ticl<. («) Slieep tick (engorged female, en- 

 larged) ; (b) true tick (engorged female, enlarged). 



During warm weather the average period of 



