156 SHEEP DISEASES. 



increases. Serum oozes from the papules, and it 

 is in this stage that the disease is first noticed. 

 When bedded down, the infected animal will get 



SHEEP-SCAB MITE (Psoroptes ovis). Female. 

 Dorsal view, greatly enlarged. 



(After Salmon and Stiles, 1898.) 



up and bite or rub its body against another or 

 some tree or post. 



The wool begins to get l ' taggy, ' ' and soon com- 

 mences to fall out. Crusts form on the skin from 

 the dried exudate. It is under the crusts that 

 the mites live. 



